G2Cdb::Gene report

Gene id
Gene symbol
Homo sapiens
discs, large homolog 3 (Drosophila)
G00000007 (Mus musculus)

Databases (9)

Curated Gene
OTTHUMG00000021778 (Vega human gene)
ENSG00000082458 (Ensembl human gene)
1741 (Entrez Gene)
13 (G2Cdb plasticity & disease)
DLG3 (GeneCards)
300189 (OMIM)
Marker Symbol
HGNC:2902 (HGNC)
Protein Expression
1733 (human protein atlas)
Protein Sequence
Q92796 (UniProt)

Synonyms (6)

  • KIAA1232
  • MRX90
  • NE-Dlg
  • SAP-102
  • SAP102

Diseases (1)

Disease Nervous effect Mutations Found Literature Mutations Type Genetic association?
D00000160: Mental retardation (X-linked) Y Y (15185169) Single nucleotide insertion (SNI) Y
D00000160: Mental retardation (X-linked) Y Y (15185169) Single nucleotide polymorphism (SNP) Y


  • Mutations in the DLG3 gene cause nonsyndromic X-linked mental retardation.

    Tarpey P, Parnau J, Blow M, Woffendin H, Bignell G, Cox C, Cox J, Davies H, Edkins S, Holden S, Korny A, Mallya U, Moon J, O'Meara S, Parker A, Stephens P, Stevens C, Teague J, Donnelly A, Mangelsdorf M, Mulley J, Partington M, Turner G, Stevenson R, Schwartz C, Young I, Easton D, Bobrow M, Futreal PA, Stratton MR, Gecz J, Wooster R and Raymond FL

    The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, United Kingdom.

    We have identified truncating mutations in the human DLG3 (neuroendocrine dlg) gene in 4 of 329 families with moderate to severe X-linked mental retardation. DLG3 encodes synapse-associated protein 102 (SAP102), a member of the membrane-associated guanylate kinase protein family. Neuronal SAP102 is expressed during early brain development and is localized to the postsynaptic density of excitatory synapses. It is composed of three amino-terminal PDZ domains, an src homology domain, and a carboxyl-terminal guanylate kinase domain. The PDZ domains interact directly with the NR2 subunits of the NMDA glutamate receptor and with other proteins responsible for NMDA receptor localization, immobilization, and signaling. The mutations identified in this study all introduce premature stop codons within or before the third PDZ domain, and it is likely that this impairs the ability of SAP102 to interact with the NMDA receptor and/or other proteins involved in downstream NMDA receptor signaling pathways. NMDA receptors have been implicated in the induction of certain forms of synaptic plasticity, such as long-term potentiation and long-term depression, and these changes in synaptic efficacy have been proposed as neural mechanisms underlying memory and learning. The disruption of NMDA receptor targeting or signaling, as a result of the loss of SAP102, may lead to altered synaptic plasticity and may explain the intellectual impairment observed in individuals with DLG3 mutations.

    Funded by: NICHD NIH HHS: HD 26202, R01 HD026202

    American journal of human genetics 2004;75;2;318-24

Literature (42)

Pubmed - other

  • Identification of new putative susceptibility genes for several psychiatric disorders by association analysis of regulatory and non-synonymous SNPs of 306 genes involved in neurotransmission and neurodevelopment.

    Gratacòs M, Costas J, de Cid R, Bayés M, González JR, Baca-García E, de Diego Y, Fernández-Aranda F, Fernández-Piqueras J, Guitart M, Martín-Santos R, Martorell L, Menchón JM, Roca M, Sáiz-Ruiz J, Sanjuán J, Torrens M, Urretavizcaya M, Valero J, Vilella E, Estivill X, Carracedo A and Psychiatric Genetics Network Group

    CIBER en Epidemiología y Salud Pública (CIBERESP), Instituto de Salud Carlos III, Madrid, Spain.

    A fundamental difficulty in human genetics research is the identification of the spectrum of genetic variants that contribute to the susceptibility to common/complex disorders. We tested here the hypothesis that functional genetic variants may confer susceptibility to several related common disorders. We analyzed five main psychiatric diagnostic categories (substance-abuse, anxiety, eating, psychotic, and mood disorders) and two different control groups, representing a total of 3,214 samples, for 748 promoter and non-synonymous single nucleotide polymorphisms (SNPs) at 306 genes involved in neurotransmission and/or neurodevelopment. We identified strong associations to individual disorders, such as growth hormone releasing hormone (GHRH) with anxiety disorders, prolactin regulatory element (PREB) with eating disorders, ionotropic kainate glutamate receptor 5 (GRIK5) with bipolar disorder and several SNPs associated to several disorders, that may represent individual and related disease susceptibility factors. Remarkably, a functional SNP, rs945032, located in the promoter region of the bradykinin receptor B2 gene (BDKRB2) was associated to three disorders (panic disorder, substance abuse, and bipolar disorder), and two additional BDKRB2 SNPs to obsessive-compulsive disorder and major depression, providing evidence for common variants of susceptibility to several related psychiatric disorders. The association of BDKRB2 (odd ratios between 1.65 and 3.06) to several psychiatric disorders supports the view that a common genetic variant could confer susceptibility to clinically related phenotypes, and defines a new functional hint in the pathophysiology of psychiatric diseases.

    American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics 2009;150B;6;808-16

  • DLG3/SAP102 protein expression in malformations of cortical development: a study of human epileptic cortex by tissue microarray.

    Qu M, Aronica E, Boer K, Fällmar D, Kumlien E, Nistér M, Wester K, Pontén F and Smits A

    Department of Neuroscience, Neurology, Uppsala University Hospital, Sweden.

    The human DLG3 gene encodes the synapse-associated protein 102 (SAP102), which is concentrated in the postsynaptic densities of excitatory synapses and involved in receptor-mediated synaptic transmission via binding to the NR2B subunit of the NMDA receptor. In this study, we investigated the expression and cellular distribution of the DLG3/SAP102 protein in human epileptic cortex. Tissue microarrays of a large number of specimens from patients operated for medically intractable epilepsy were used for immunohistochemical screening with anti-DLG3 antibody. The cellular distribution of the protein was further investigated in samples of malformations of cortical development, and the amount of DLG3 protein in the total homogenate and in the postsynaptic membrane fraction of these samples was quantified by Western blot. We found a strictly neuronal expression of DLG3/SAP102 in epileptogenic cortex as well as in non-epileptic human cortex used for control. In focal cortical dysplasia and tuberous sclerosis complex, the protein was expressed in most neurons including dysplastic neurons, but not in giant cells. Increased expression of DLG3 protein was observed in the postsynaptic membrane fraction of patients with focal cortical dysplasia. Double-labeling experiments confirmed the exclusive neuronal character of the DLG3 expressing cells and the co-localization of the DLG3 protein with the NR2B subunit. Our results suggest a putative role for DLG3/SAP102 in cortical hyperexcitability and epileptogenicity of malformations of cortical development.

    Epilepsy research 2009;84;1;33-41

  • Preso, a novel PSD-95-interacting FERM and PDZ domain protein that regulates dendritic spine morphogenesis.

    Lee HW, Choi J, Shin H, Kim K, Yang J, Na M, Choi SY, Kang GB, Eom SH, Kim H and Kim E

    National Creative Research Initiative Center for Synaptogenesis and Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea.

    PSD-95 is an abundant postsynaptic density (PSD) protein involved in the formation and regulation of excitatory synapses and dendritic spines, but the underlying mechanisms are not comprehensively understood. Here we report a novel PSD-95-interacting protein Preso that regulates spine morphogenesis. Preso is mainly expressed in the brain and contains WW (domain with two conserved Trp residues), PDZ (PSD-95/Dlg/ZO-1), FERM (4.1, ezrin, radixin, and moesin), and C-terminal PDZ-binding domains. These domains associate with actin filaments, the Rac1/Cdc42 guanine nucleotide exchange factor betaPix, phosphatidylinositol-4,5-bisphosphate, and the postsynaptic scaffolding protein PSD-95, respectively. Preso overexpression increases the density of dendritic spines in a manner requiring WW, PDZ, FERM, and PDZ-binding domains. Conversely, knockdown or dominant-negative inhibition of Preso decreases spine density, excitatory synaptic transmission, and the spine level of filamentous actin. These results suggest that Preso positively regulates spine density through its interaction with the synaptic plasma membrane, actin filaments, PSD-95, and the betaPix-based Rac1 signaling pathway.

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2008;28;53;14546-56

  • Toward a confocal subcellular atlas of the human proteome.

    Barbe L, Lundberg E, Oksvold P, Stenius A, Lewin E, Björling E, Asplund A, Pontén F, Brismar H, Uhlén M and Andersson-Svahn H

    Department of Biotechnology, AlbaNova University Center, Royal Institute of Technology, SE-106 91 Stockholm, Sweden.

    Information on protein localization on the subcellular level is important to map and characterize the proteome and to better understand cellular functions of proteins. Here we report on a pilot study of 466 proteins in three human cell lines aimed to allow large scale confocal microscopy analysis using protein-specific antibodies. Approximately 3000 high resolution images were generated, and more than 80% of the analyzed proteins could be classified in one or multiple subcellular compartment(s). The localizations of the proteins showed, in many cases, good agreement with the Gene Ontology localization prediction model. This is the first large scale antibody-based study to localize proteins into subcellular compartments using antibodies and confocal microscopy. The results suggest that this approach might be a valuable tool in conjunction with predictive models for protein localization.

    Molecular & cellular proteomics : MCP 2008;7;3;499-508

  • Large-scale mapping of human protein-protein interactions by mass spectrometry.

    Ewing RM, Chu P, Elisma F, Li H, Taylor P, Climie S, McBroom-Cerajewski L, Robinson MD, O'Connor L, Li M, Taylor R, Dharsee M, Ho Y, Heilbut A, Moore L, Zhang S, Ornatsky O, Bukhman YV, Ethier M, Sheng Y, Vasilescu J, Abu-Farha M, Lambert JP, Duewel HS, Stewart II, Kuehl B, Hogue K, Colwill K, Gladwish K, Muskat B, Kinach R, Adams SL, Moran MF, Morin GB, Topaloglou T and Figeys D

    Protana, Toronto, Ontario, Canada.

    Mapping protein-protein interactions is an invaluable tool for understanding protein function. Here, we report the first large-scale study of protein-protein interactions in human cells using a mass spectrometry-based approach. The study maps protein interactions for 338 bait proteins that were selected based on known or suspected disease and functional associations. Large-scale immunoprecipitation of Flag-tagged versions of these proteins followed by LC-ESI-MS/MS analysis resulted in the identification of 24,540 potential protein interactions. False positives and redundant hits were filtered out using empirical criteria and a calculated interaction confidence score, producing a data set of 6463 interactions between 2235 distinct proteins. This data set was further cross-validated using previously published and predicted human protein interactions. In-depth mining of the data set shows that it represents a valuable source of novel protein-protein interactions with relevance to human diseases. In addition, via our preliminary analysis, we report many novel protein interactions and pathway associations.

    Molecular systems biology 2007;3;89

  • Uncovering quantitative protein interaction networks for mouse PDZ domains using protein microarrays.

    Stiffler MA, Grantcharova VP, Sevecka M and MacBeath G

    Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.

    One of the principal challenges in systems biology is to uncover the networks of protein-protein interactions that underlie most biological processes. To date, experimental efforts directed at this problem have largely produced only qualitative networks that are replete with false positives and false negatives. Here, we describe a domain-centered approach--compatible with genome-wide investigations--that enables us to measure the equilibrium dissociation constant (K(D)) of recombinant PDZ domains for fluorescently labeled peptides that represent physiologically relevant binding partners. Using a pilot set of 22 PDZ domains, 4 PDZ domain clusters, and 20 peptides, we define a gold standard dataset by determining the K(D) for all 520 PDZ-peptide combinations using fluorescence polarization. We then show that microarrays of PDZ domains identify interactions of moderate to high affinity (K(D) < or = 10 microM) in a high-throughput format with a false positive rate of 14% and a false negative rate of 14%. By combining the throughput of protein microarrays with the fidelity of fluorescence polarization, our domain/peptide-based strategy yields a quantitative network that faithfully recapitulates 85% of previously reported interactions and uncovers new biophysical interactions, many of which occur between proteins that are co-expressed. From a broader perspective, the selectivity data produced by this effort reveal a strong concordance between protein sequence and protein function, supporting a model in which interaction networks evolve through small steps that do not involve dramatic rewiring of the network.

    Funded by: NIGMS NIH HHS: 1 R01 GM072872-01, 5 T32 GM07598-25, R01 GM072872, R01 GM072872-04, T32 GM007598

    Journal of the American Chemical Society 2006;128;17;5913-22

  • Involvement of a cellular ubiquitin-protein ligase E6AP in the ubiquitin-mediated degradation of extensive substrates of high-risk human papillomavirus E6.

    Matsumoto Y, Nakagawa S, Yano T, Takizawa S, Nagasaka K, Nakagawa K, Minaguchi T, Wada O, Ooishi H, Matsumoto K, Yasugi T, Kanda T, Huibregtse JM and Taketani Y

    Department of Obstetrics and Gynecology, Graduate School of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan.

    Human scribble (hScrib), which was identified as substrate of human papillomavirus (HPV) E6 for ubiquitin-mediated degradation dependent on ubiquitin-protein ligase E6AP, is a human homolog of Drosophila neoplastic tumor suppressor scribble, in which mutation causes loss of polarity and overgrowth of epithelia. Drosophila discs large (Dlg) is one of neoplastic tumor suppressors, which genetically links to scribble. E6 also targets human Dlg (hDlg) for ubiquitin-mediated degradation. Ubiquitin-protein ligase involved in this process has not been identified thus far. Here we investigated mechanism underlying degradation of three target proteins of E6, hScrib, hDlg, and p53 by using eighteen HPV 16 E6 mutants with single amino acid substitution. In vitro degradation ability of each E6 mutant was equivalent for these tumor suppressors. We investigated whether E6AP is involved in ubiquitin-mediated degradation of hDlg. In vitro binding assay revealed that hDlg formed ternary complex with E6-E6AP complex. The ability of E6 mutants to degrade these tumor suppressors was correlated with their ability to interact with E6AP. Furthermore, hDlg was targeted for in vitro ubiquitination in the presence of both E6 and E6AP. These data revealed that E6AP is extensively involved in the ubiquitin-mediated degradation of E6-dependent substrates as a cellular E3 ubiquitin-protein ligase.

    Journal of medical virology 2006;78;4;501-7

  • HDAC6 and microtubules are required for autophagic degradation of aggregated huntingtin.

    Iwata A, Riley BE, Johnston JA and Kopito RR

    Department of Biological Sciences, BIO-X Program, Stanford University, Stanford, California 94305-5430, USA.

    CNS neurons are endowed with the ability to recover from cytotoxic insults associated with the accumulation of proteinaceous polyglutamine aggregates via a process that appears to involve capture and degradation of aggregates by autophagy. The ubiquitin-proteasome system protects cells against proteotoxicity by degrading soluble monomeric misfolded aggregation-prone proteins but is ineffective against, and impaired by, non-native protein oligomers. Here we show that autophagy is induced in response to impaired ubiquitin proteasome system activity. We show that ATG proteins, molecular determinants of autophagic vacuole formation, and lysosomes are recruited to pericentriolar cytoplasmic inclusion bodies by a process requiring an intact microtubule cytoskeleton and the cytoplasmic deacetylase HDAC6. These data suggest that HDAC6-dependent retrograde transport on microtubules is used by cells to increase the efficiency and selectivity of autophagic degradation.

    Funded by: NINDS NIH HHS: NS-042842

    The Journal of biological chemistry 2005;280;48;40282-92

  • Purification of ATP-binding cassette transporter A1 and associated binding proteins reveals the importance of beta1-syntrophin in cholesterol efflux.

    Okuhira K, Fitzgerald ML, Sarracino DA, Manning JJ, Bell SA, Goss JL and Freeman MW

    Lipid Metabolism Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.

    ATP-binding cassette transporter A1 (ABCA1) plays a critical role in HDL cholesterol metabolism, but the mechanism by which it transports lipid across membranes is poorly understood. Because growing evidence implicates accessory proteins in this process, we developed a method by which proteins interacting with the intact transporter could be identified. cDNAs encoding wild-type ABCA1 and a mutant lacking the C-terminal PDZ binding motif of ABCA1 were transfected into 293 cells, and the expressed proteins were solubilized using detergent conditions (0.75% CHAPS, 1 mg/ml phosphatidylcholine) predicted to retain high affinity protein-protein interactions. Proteins that co-purified with ABCA1 on an antibody affinity column were identified by liquid chromatographymass spectrometric analysis. A novel interaction with the PDZ protein beta1-syntrophin was identified using this approach, and this interaction was confirmed in human THP-1 macrophages and in mouse liver. Small interference RNA inhibition of beta1-syntrophin expression reduced cholesterol efflux from primary skin fibroblasts by 50% while decreasing efflux 30% in bone marrow-derived macrophages. Inhibition of beta1-syntrophin decreased ABCA1 protein levels, whereas overexpression of beta1-syntrophin increased ABCA1 cell-surface expression and stimulated efflux to apolipoprotein A-I. These findings indicate that beta1-syntrophin acts through a class-I PDZ interaction with the C terminus of ABCA1 to regulate the cellular distribution and activity of the transporter. The approach used to identify beta1-syntrophin as an ABCA1-binding protein should prove useful in elucidating other protein interactions upon which ABCA1 function depends.

    Funded by: NHLBI NIH HHS: HL074136, HL45098, HL68988, HL72358

    The Journal of biological chemistry 2005;280;47;39653-64

  • Mutations in the DLG3 gene cause nonsyndromic X-linked mental retardation.

    Tarpey P, Parnau J, Blow M, Woffendin H, Bignell G, Cox C, Cox J, Davies H, Edkins S, Holden S, Korny A, Mallya U, Moon J, O'Meara S, Parker A, Stephens P, Stevens C, Teague J, Donnelly A, Mangelsdorf M, Mulley J, Partington M, Turner G, Stevenson R, Schwartz C, Young I, Easton D, Bobrow M, Futreal PA, Stratton MR, Gecz J, Wooster R and Raymond FL

    The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, United Kingdom.

    We have identified truncating mutations in the human DLG3 (neuroendocrine dlg) gene in 4 of 329 families with moderate to severe X-linked mental retardation. DLG3 encodes synapse-associated protein 102 (SAP102), a member of the membrane-associated guanylate kinase protein family. Neuronal SAP102 is expressed during early brain development and is localized to the postsynaptic density of excitatory synapses. It is composed of three amino-terminal PDZ domains, an src homology domain, and a carboxyl-terminal guanylate kinase domain. The PDZ domains interact directly with the NR2 subunits of the NMDA glutamate receptor and with other proteins responsible for NMDA receptor localization, immobilization, and signaling. The mutations identified in this study all introduce premature stop codons within or before the third PDZ domain, and it is likely that this impairs the ability of SAP102 to interact with the NMDA receptor and/or other proteins involved in downstream NMDA receptor signaling pathways. NMDA receptors have been implicated in the induction of certain forms of synaptic plasticity, such as long-term potentiation and long-term depression, and these changes in synaptic efficacy have been proposed as neural mechanisms underlying memory and learning. The disruption of NMDA receptor targeting or signaling, as a result of the loss of SAP102, may lead to altered synaptic plasticity and may explain the intellectual impairment observed in individuals with DLG3 mutations.

    Funded by: NICHD NIH HHS: HD 26202, R01 HD026202

    American journal of human genetics 2004;75;2;318-24

  • Transcriptome characterization elucidates signaling networks that control human ES cell growth and differentiation.

    Brandenberger R, Wei H, Zhang S, Lei S, Murage J, Fisk GJ, Li Y, Xu C, Fang R, Guegler K, Rao MS, Mandalam R, Lebkowski J and Stanton LW

    Geron Corporation, Menlo Park, California 94025, USA. rbrandenberger@geron.com

    Human embryonic stem (hES) cells hold promise for generating an unlimited supply of cells for replacement therapies. To characterize hES cells at the molecular level, we obtained 148,453 expressed sequence tags (ESTs) from undifferentiated hES cells and three differentiated derivative subpopulations. Over 32,000 different transcripts expressed in hES cells were identified, of which more than 16,000 do not match closely any gene in the UniGene public database. Queries to this EST database revealed 532 significantly upregulated and 140 significantly downregulated genes in undifferentiated hES cells. These data highlight changes in the transcriptional network that occur when hES cells differentiate. Among the differentially regulated genes are several components of signaling pathways and transcriptional regulators that likely play key roles in hES cell growth and differentiation. The genomic data presented here may facilitate the derivation of clinically useful cell types from hES cells.

    Nature biotechnology 2004;22;6;707-16

  • Protein trafficking and anchoring complexes revealed by proteomic analysis of inward rectifier potassium channel (Kir2.x)-associated proteins.

    Leonoudakis D, Conti LR, Anderson S, Radeke CM, McGuire LM, Adams ME, Froehner SC, Yates JR and Vandenberg CA

    Department of Molecular, Cellular, University of California, Santa Barbara, California 93106, USA.

    Inward rectifier potassium (Kir) channels play important roles in the maintenance and control of cell excitability. Both intracellular trafficking and modulation of Kir channel activity are regulated by protein-protein interactions. We adopted a proteomics approach to identify proteins associated with Kir2 channels via the channel C-terminal PDZ binding motif. Detergent-solubilized rat brain and heart extracts were subjected to affinity chromatography using a Kir2.2 C-terminal matrix to purify channel-interacting proteins. Proteins were identified with multidimensional high pressure liquid chromatography coupled with electrospray ionization tandem mass spectrometry, N-terminal microsequencing, and immunoblotting with specific antibodies. We identified eight members of the MAGUK family of proteins (SAP97, PSD-95, Chapsyn-110, SAP102, CASK, Dlg2, Dlg3, and Pals2), two isoforms of Veli (Veli-1 and Veli-3), Mint1, and actin-binding LIM protein (abLIM) as Kir2.2-associated brain proteins. From heart extract purifications, SAP97, CASK, Veli-3, and Mint1 also were found to associate with Kir2 channels. Furthermore, we demonstrate for the first time that components of the dystrophin-associated protein complex, including alpha1-, beta1-, and beta2-syntrophin, dystrophin, and dystrobrevin, interact with Kir2 channels, as demonstrated by immunoaffinity purification and affinity chromatography from skeletal and cardiac muscle and brain. Affinity pull-down experiments revealed that Kir2.1, Kir2.2, Kir2.3, and Kir4.1 all bind to scaffolding proteins but with different affinities for the dystrophin-associated protein complex and SAP97, CASK, and Veli. Immunofluorescent localization studies demonstrated that Kir2.2 co-localizes with syntrophin, dystrophin, and dystrobrevin at skeletal muscle neuromuscular junctions. These results suggest that Kir2 channels associate with protein complexes that may be important to target and traffic channels to specific subcellular locations, as well as anchor and stabilize channels in the plasma membrane.

    Funded by: NINDS NIH HHS: NS33145, NS43377

    The Journal of biological chemistry 2004;279;21;22331-46

  • Selective interaction of megalin with postsynaptic density-95 (PSD-95)-like membrane-associated guanylate kinase (MAGUK) proteins.

    Larsson M, Hjälm G, Sakwe AM, Engström A, Höglund AS, Larsson E, Robinson RC, Sundberg C and Rask L

    Department of Medical Biochemistry and Microbiology, Uppsala University, PO Box 582, SE-751 23 Uppsala, Sweden. Marten.Larsson@imbim.uu.se

    Megalin is an integral membrane receptor belonging to the low-density lipoprotein receptor family. In addition to its role as an endocytotic receptor, megalin has also been proposed to have signalling functions. Using interaction cloning in yeast, we identified the membrane-associated guanylate kinase family member postsynaptic density-95 (PSD-95) as an interaction partner for megalin. PSD-95 and a truncated version of megalin were co-immunoprecipitated from HEK-293 cell lysates overexpressing the two proteins, which confirmed the interaction. The two proteins were found to be co-localized in these cells by confocal microscopy. Immunocytochemical studies showed that cells in the parathyroid, proximal tubuli of the kidney and placenta express both megalin and PSD-95. We found that the interaction between the two proteins is mediated by the binding of the C-terminus of megalin, which has a type I PSD-95/ Drosophila discs-large/zona occludens 1 (PDZ)-binding motif, to the PDZ2 domain of PSD-95. The PSD-95-like membrane-associated guanylate kinase ('MAGUK') family contains three additional members: PSD-93, synapse-associated protein 97 (SAP97) and SAP102. We detected these proteins, apart from SAP102, in parathyroid chief cells, a cell type having a marked expression of megalin. The PDZ2 domains of PSD-93 and SAP102 were also shown to interact with megalin, whereas no interaction was detected for SAP97. The SAP97 PDZ2 domain differed at four positions from the other members of the PSD-95 subfamily. One of these residues was Thr(389), located in the alphaB-helix and part of the hydrophobic pocket of the PDZ2 domain. Surface plasmon resonance experiments revealed that mutation of SAP97 Thr(389) to alanine, as with the other PSD-95-like membrane-associated guanylate kinases, induced binding to megalin.

    The Biochemical journal 2003;373;Pt 2;381-91

  • NMDA receptor trafficking through an interaction between PDZ proteins and the exocyst complex.

    Sans N, Prybylowski K, Petralia RS, Chang K, Wang YX, Racca C, Vicini S and Wenthold RJ

    Laboratory of Neurochemistry, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Building 50, Room 4146, 50 South Drive, Bethesda, MD 20892-8027, USA. sansn@nidcd.nih.gov

    NMDA (N-methyl-D-aspartate) receptors (NMDARs) are targeted to dendrites and anchored at the post-synaptic density (PSD) through interactions with PDZ proteins. However, little is known about how these receptors are sorted from the endoplasmic reticulum and Golgi apparatus to the synapse. Here, we find that synapse-associated protein 102 (SAP102) interacts with the PDZ-binding domain of Sec8, a member of the exocyst complex. Our results show that interactions between SAP102 and Sec8 are involved in the delivery of NMDARs to the cell surface in heterologous cells and neurons. Furthermore, they suggest that an exocyst-SAP102-NMDAR complex is an important component of NMDAR trafficking.

    Nature cell biology 2003;5;6;520-30

  • Interaction of the tyrosine kinase Pyk2 with the N-methyl-D-aspartate receptor complex via the Src homology 3 domains of PSD-95 and SAP102.

    Seabold GK, Burette A, Lim IA, Weinberg RJ and Hell JW

    Department of Pharmacology, University of Wisconsin, Madison, Wisconsin 53706-1532, USA.

    The protein-tyrosine kinase Pyk2/CAKbeta/CADTK is a key activator of Src in many cells. At hippocampal synapses, induction of long term potentiation requires the Pyk2/Src signaling pathway, which up-regulates the activity of N-methyl-d-aspartate-type glutamate receptors. Because localization of protein kinases close to their substrates is crucial for effective phosphorylation, we investigated how Pyk2 might be recruited to the N-methyl-d-aspartate receptor complex. This interaction is mediated by PSD-95 and its homolog SAP102. Both proteins colocalize with Pyk2 at postsynaptic dendritic spines in the cerebral cortex. The proline-rich regions in the C-terminal half of Pyk2 bind to the SH3 domain of PSD-95 and SAP102. The SH3 and guanylate kinase homology (GK) domain of PSD-95 and SAP102 interact intramolecularly, but the physiological significance of this interaction has been unclear. We show that Pyk2 effectively binds to the Src homology 3 (SH3) domain of SAP102 only when the GK domain is removed from the SH3 domain. Characterization of PSD-95 and SAP102 as adaptor proteins for Pyk2 fills a critical gap in the understanding of the spatial organization of the Pyk2-Src signaling pathway at the postsynaptic site and reveals a physiological function of the intramolecular SH3-GK domain interaction in SAP102.

    Funded by: NIA NIH HHS: AG17502; NINDS NIH HHS: NS35563, NS39444

    The Journal of biological chemistry 2003;278;17;15040-8

  • Identification of multiple binding partners for the amino-terminal domain of synapse-associated protein 97.

    Karnak D, Lee S and Margolis B

    Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.

    Multiprotein complexes mediate static and dynamic functions to establish and maintain cell polarity in both epithelial cells and neurons. Membrane-associated guanylate kinase (MAGUK) proteins are thought to be scaffolding molecules in these processes and bind multiple proteins via their obligate postsynaptic density (PSD)-95/Disc Large/Zona Occludens-1, Src homology 3, and guanylate kinase-like domains. Subsets of MAGUK proteins have additional protein-protein interaction domains. An additional domain we identified in SAP97 called the MAGUK recruitment (MRE) domain binds the LIN-2,7 amino-terminal (L27N) domain of mLIN-2/CASK, a MAGUK known to bind mLIN-7. Here we show that SAP97 binds two other mLIN-7 binding MAGUK proteins. One of these MAGUK proteins, DLG3, coimmunoprecipitates with SAP97 in lysates from rat brain and transfected Madin-Darby canine kidney cells. This interaction requires the MRE domain of SAP97 and surprisingly, both the L27N and L27 carboxyl-terminal (L27C) domains of DLG3. We also demonstrate that SAP97 can interact with the MAGUK protein, DLG2, but not the highly related protein, PALS2. The ability of SAP97 to interact with multiple MAGUK proteins is likely to be important for the targeting of specific protein complexes in polarized cells.

    Funded by: NIDDK NIH HHS: 2-P50-DK39255; NIGMS NIH HHS: 5-T32-GM07544, GM08353

    The Journal of biological chemistry 2002;277;48;46730-5

  • Selective binding of synapse-associated protein 97 to GluR-A alpha-amino-5-hydroxy-3-methyl-4-isoxazole propionate receptor subunit is determined by a novel sequence motif.

    Cai C, Coleman SK, Niemi K and Keinänen K

    Department of Biosciences, Division of Biochemistry, University of Helsinki, Helsinki FIN-00014, Finland.

    A family of four closely related PDZ domain-containing membrane-associated guanylate kinase homologues (MAGUKs) is involved in the regulation of the amount and functional state of ionotropic glutamate receptors in excitatory synapses. To understand the mechanisms that determine the specificity of these interactions, we examined the structural basis of the highly selective association between the ionotropic GluR subunit GluR-A and synapse-associated protein 97 (SAP97). The C terminus of GluR-A bound to the PDZ domains of SAP97, but not to those of three related MAGUKs, PSD-93, PSD-95, and SAP102. Experiments with single PDZ domains indicated that the strongest contribution was by the second PDZ domain. Unexpectedly, mutation analysis of the GluR-A C terminus revealed that a tripeptide sequence SSG at position -9 to -11 plays an essential role in this binding, in addition to a C-terminal type I PDZ binding motif (leucine at C terminus and threonine at the -2 position). Analysis of the in vitro MAGUK-binding properties of a GluR-D mutant with a one-residue deletion at the C terminus provides further support for the view that an SSG sequence located N-terminally from a type I PDZ binding motif can mediate selective binding to SAP97 and suggest the existence of a novel variation of the PDZ domain-peptide interaction.

    The Journal of biological chemistry 2002;277;35;31484-90

  • Selectivity and promiscuity of the first and second PDZ domains of PSD-95 and synapse-associated protein 102.

    Lim IA, Hall DD and Hell JW

    Department of Pharmacology, University of Wisconsin, Madison, Wisconsin 53706-1532, USA.

    PDZ domains typically interact with the very carboxyl terminus of their binding partners. Type 1 PDZ domains usually require valine, leucine, or isoleucine at the very COOH-terminal (P(0)) position, and serine or threonine 2 residues upstream at P(-2). We quantitatively defined the contributions of carboxyl-terminal residues to binding selectivity of the prototypic interactions of the PDZ domains of postsynaptic density protein 95 (PSD-95) and its homolog synapse-associated protein 90 (SAP102) with the NR2b subunit of the N-methyl-d-aspartate-type glutamate receptor. Our studies indicate that all of the last five residues of NR2b contribute to the binding selectivity. Prominent were a requirement for glutamate or glutamine at P(-3) and for valine at P(0) for high affinity binding and a preference for threonine over serine at P(-2), in the context of the last 11 residues of the NR2b COOH terminus. This analysis predicts a COOH-terminal (E/Q)(S/T)XV consensus sequence for the strongest binding to the first two PDZ domains of PSD-95 and SAP102. A search of the human genome sequences for proteins with a COOH-terminal (E/Q)(S/T)XV motif yielded 50 proteins, many of which have not been previously identified as PSD-95 or SAP102 binding partners. Two of these proteins, brain-specific angiogenesis inhibitor 1 and protein kinase Calpha, co-immunoprecipitated with PSD-95 and SAP102 from rat brain extracts.

    Funded by: NIA NIH HHS: AG00213; NIDDK NIH HHS: DK07759; NINDS NIH HHS: R01-NS35563

    The Journal of biological chemistry 2002;277;24;21697-711

  • Compartmentalized NRG signaling and PDZ domain-containing proteins in synapse structure and function.

    Huang YZ, Wang Q, Won S, Luo ZG, Xiong WC and Mei L

    Department of Neurobiology, Pathology, Physical Medicine and Rehabilitation, University of Alabama at Birmingham, 35294-0021, USA.

    The synapse-specific synthesis of the acetylcholine receptor (AChR) is mediated by multiple mechanisms including compartmentalized signaling induced by neuregulin (NRG). This paper presents evidence that NRG receptors--ErbB receptor tyrosine kinases interact with distinct PDZ domain-containing proteins that are localized at the neuromuscular junction (NMJ). ErbB4 associates with the PSD-95 (also known as SAP90)-family members including PSD-95, SAP97, and SAP102 whereas ErbB2 interacts with Erbin and PICK1. Although, ErbB kinases are concentrated at the NMJ, they are not colocalized with the AChR in cultured muscle cells even in the presence of agrin. Co-expression of PSD-95 causes ErbB4 to form clusters in COS cells. We propose that PDZ domain-containing proteins play a role in anchoring ErbB proteins at the neuromuscular junction, and/or mediating downstream signaling pathways. Such mechanisms could be important for the maintenance and function of the synapse.

    Funded by: NICHD NIH HHS: P30HD38985

    International journal of developmental neuroscience : the official journal of the International Society for Developmental Neuroscience 2002;20;3-5;173-85

  • Inward rectifier K+ channel Kir2.3 is localized at the postsynaptic membrane of excitatory synapses.

    Inanobe A, Fujita A, Ito M, Tomoike H, Inageda K and Kurachi Y

    Department of Pharmacology II, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.

    Classical inwardly rectifying K+ channels (Kir2.0) are responsible for maintaining the resting membrane potential near the K+ equilibrium potential in various cells, including neurons. Although Kir2.3 is known to be expressed abundantly in the forebrain, its precise localization has not been identified. Using an antibody specific to Kir2.3, we examined the subcellular localization of Kir2.3 in mouse brain. Kir2.3 immunoreactivity was detected in a granular pattern in restricted areas of the brain, including the olfactory bulb (OB). Immunoelectron microscopy of the OB revealed that Kir2.3 immunoreactivity was specifically clustered on the postsynaptic membrane of asymmetric synapses between granule cells and mitral/tufted cells. The immunoprecipitants for Kir2.3 obtained from brain contained PSD-95 and chapsyn-110, PDZ domain-containing anchoring proteins. In vitro binding assay further revealed that the COOH-terminal end of Kir2.3 is responsible for the association with these anchoring proteins. Therefore, the Kir channel may be involved in formation of the resting membrane potential of the spines and, thus, would affect the response of N-methyl-D-aspartic acid receptor channels at the excitatory postsynaptic membrane.

    American journal of physiology. Cell physiology 2002;282;6;C1396-403

  • Guanylyl cyclase/PSD-95 interaction: targeting of the nitric oxide-sensitive alpha2beta1 guanylyl cyclase to synaptic membranes.

    Russwurm M, Wittau N and Koesling D

    Pharmakologie und Toxikologie, Medizinische Fakultät MA N1, Ruhr-Universität Bochum, 44780 Bochum, Germany.

    The signaling molecule nitric oxide (NO) exerts most of its effects by the stimulation of the NO-sensitive guanylyl cyclase. Two isoforms of the NO receptor molecule exist: the ubiquitously occurring alpha(1)beta(1) and the alpha(2)beta(1) with a more limited distribution. As the isoforms are functionally indistinguishable, the physiological relevance of these isoforms remained unclear. The neuronal NO synthase has been reported to be associated with PSD-95. Here, we demonstrate the interaction of the so far unnoticed alpha(2)beta(1) isoform with PSD-95 in rat brain as shown by coprecipitation. The interaction is mediated by the alpha(2) C-terminal peptide and the third PDZ domain of PSD-95. As a consequence of the PSD-95 interaction, the so far considered "soluble" alpha(2)beta(1) isoform is recruited to the membrane fraction of synaptosomes, whereas the alpha(1)beta(1) isoform is found in the cytosol. Our results establish the alpha(1)beta(1) as the cytosolic and the alpha(2)beta(1) as the membrane-associated NO-sensitive guanylyl cyclase and suggest the alpha(2)beta(1) isoform as the sensor for the NO formed by the PSD-95-associated neuronal NO synthase.

    The Journal of biological chemistry 2001;276;48;44647-52

  • Plasma membrane Ca2+-atpase isoforms 2b and 4b interact promiscuously and selectively with members of the membrane-associated guanylate kinase family of PDZ (PSD95/Dlg/ZO-1) domain-containing proteins.

    DeMarco SJ and Strehler EE

    Program in Molecular Neuroscience, Department of Biochemistry, Mayo Graduate School, Mayo Clinic, Rochester, Minnesota 55905, USA.

    Spatial and temporal regulation of intracellular Ca(2+) signaling depends on localized Ca(2+) microdomains containing the requisite molecular components for Ca(2+) influx, efflux, and signal transmission. Plasma membrane Ca(2+)-ATPase (PMCA) isoforms of the "b" splice type contain predicted PDZ (PSD95/Dlg/ZO-1) interaction domains. The COOH-terminal tail of PMCA2b isolated the membrane-associated guanylate kinase (MAGUK) protein SAP97/hDlg as a binding partner in a yeast two-hybrid screen. The related MAGUKs SAP90/PSD95, PSD93/chapsyn-110, SAP97, and SAP102 all bound to the COOH-terminal tail of PMCA4b, whereas only the first three bound to the tail of PMCA2b. Coimmunoprecipitations confirmed the interaction selectivity between PMCA4b and SAP102 as opposed to the promiscuity of PMCA2b and 4b in interacting with other SAPs. Confocal immunofluorescence microscopy revealed the exclusive presence and colocalization of PMCA4b and SAP97 in the basolateral membrane of polarized Madin-Darby canine kidney epithelial cells. In hippocampal neurons, PMCA2b was abundant throughout the somatodendritic compartment and often extended into the neck and head of individual spines where it colocalized with SAP90/PSD95. These data show that PMCA "b" splice forms interact promiscuously but also with specificity with different members of the PSD95 family of SAPs. PMCA-SAP interactions may play a role in the recruitment and maintenance of the PMCA at specific membrane domains involved in local Ca(2+) regulation.

    Funded by: NIGMS NIH HHS: GM-58710

    The Journal of biological chemistry 2001;276;24;21594-600

  • Sema4c, a transmembrane semaphorin, interacts with a post-synaptic density protein, PSD-95.

    Inagaki S, Ohoka Y, Sugimoto H, Fujioka S, Amazaki M, Kurinami H, Miyazaki N, Tohyama M and Furuyama T

    Group of Neurobiology, School of Allied Health Sciences, Osaka University Faculty of Medicine, Yamadaoka 1-7, Suita-shi, Osaka, 565-0871, Japan. inagaki@sahs.med.osaka-u.ac.jp

    Semaphorins are known to act as chemorepulsive molecules that guide axons during neural development. Sema4C, a group 4 semaphorin, is a transmembrane semaphorin of unknown function. The cytoplasmic domain of Sema4C contains a proline-rich region that may interact with some signaling proteins. In this study, we demonstrate that Sema4C is enriched in the adult mouse brain and associated with PSD-95 isoforms containing PDZ (PSD-95/DLG/ZO-1) domains, such as PSD-95/SAP90, PSD-93/chapsin110, and SAP97/DLG-1, which are concentrated in the post-synaptic density of the brain. In the neocortex, S4C is enriched in the synaptic vesicle fraction and Triton X-100 insoluble post-synaptic density fraction. Immunostaining for Sema4C overlaps that for PSD-95 in superficial layers I-IV of the neocortex. In neocortical culture, S4C is colocalized with PSD-95 in neurons, with a dot-like pattern along the neurites. Sema4C thus may function in the cortical neurons as a bi-directional transmembrane ligand through interacting with PSD-95.

    The Journal of biological chemistry 2001;276;12;9174-81

  • The G protein-coupled receptor CL1 interacts directly with proteins of the Shank family.

    Tobaben S, Südhof TC and Stahl B

    Max Planck-Institute for Experimental Medicine, 37075 Göttingen, Germany.

    PDZ domains play a pivotal role in the synaptic localization of ion channels, receptors, signaling enzymes, and cell adhesion molecules. These domains mediate protein-protein interactions via the recognition of a conserved sequence motif at the extreme C terminus of their target proteins. By means of a yeast two-hybrid screen using the C terminus of the G protein-coupled alpha-latrotoxin receptor CL1 as bait, three PDZ domain proteins of the Shank family were identified. These proteins belong to a single protein family characterized by a common domain organization. The PDZ domain is highly conserved among the family members, significantly different from other known PDZ domains, and specifically binds to the C terminus of CL1. Shank1 and CL1 are expressed primarily in brain, and both proteins co-enrich in the postsynaptic density. Furthermore, Shank1 induces a clustering of CL1 in transfected cells, strongly supporting an interaction of both proteins in vivo.

    The Journal of biological chemistry 2000;275;46;36204-10

  • Proteomic analysis of NMDA receptor-adhesion protein signaling complexes.

    Husi H, Ward MA, Choudhary JS, Blackstock WP and Grant SG

    Centre for Genome Research, Centre for Neuroscience, University of Edinburgh, West Mains Road, Edinburgh EH9 3JQ, UK.

    N-methyl-d-aspartate receptors (NMDAR) mediate long-lasting changes in synapse strength via downstream signaling pathways. We report proteomic characterization with mass spectrometry and immunoblotting of NMDAR multiprotein complexes (NRC) isolated from mouse brain. The NRC comprised 77 proteins organized into receptor, adaptor, signaling, cytoskeletal and novel proteins, of which 30 are implicated from binding studies and another 19 participate in NMDAR signaling. NMDAR and metabotropic glutamate receptor subtypes were linked to cadherins and L1 cell-adhesion molecules in complexes lacking AMPA receptors. These neurotransmitter-adhesion receptor complexes were bound to kinases, phosphatases, GTPase-activating proteins and Ras with effectors including MAPK pathway components. Several proteins were encoded by activity-dependent genes. Genetic or pharmacological interference with 15 NRC proteins impairs learning and with 22 proteins alters synaptic plasticity in rodents. Mutations in three human genes (NF1, Rsk-2, L1) are associated with learning impairments, indicating the NRC also participates in human cognition.

    Nature neuroscience 2000;3;7;661-9

  • The neuregulin receptor ErbB-4 interacts with PDZ-containing proteins at neuronal synapses.

    Garcia RA, Vasudevan K and Buonanno A

    Unit on Molecular Neurobiology, National Institutes of Health, Bethesda, MD 20892, USA.

    Neuregulins regulate the expression of ligand- and voltage-gated channels in neurons and skeletal muscle by the activation of their cognate tyrosine kinase receptors, ErbB 1-4. The subcellular distribution and mechanisms that regulate the localization of ErbB receptors are unknown. We have found that ErbB receptors are present in brain subcellular fractions enriched for postsynaptic densities (PSD). The ErbB-4 receptor is unique among the ErbB proteins because its C-terminal tail (T-V-V) conforms to a sequence that binds to a protein motif known as the PDZ domain. Using the yeast two-hybrid system, we found that the C-terminal region of ErbB-4 interacts with the three related membrane-associated guanylate kinases (MAGUKs) PSD-95/SAP90, PSD-93/chapsyn-110, and SAP 102, which harbor three PDZ domains, as well as with beta(2)-syntrophin, which has a single PDZ domain. As with N-methyl-D-aspartate (NMDA) receptors, ErbB4 interacts with the first two PDZ domains of PSD-95. Using coimmunoprecipitation assays, we confirmed the direct interactions between ErbB-4 and PSD-95 in transfected heterologous cells, as well as in vivo, where both proteins are coimmunoprecipitated from brain lysates. Moreover, evidence for colocalization of these proteins was also observed by immunofluorescence in cultured hippocampal neurons. ErbB-4 colocalizes with PSD-95 and NMDA receptors at a subset of excitatory synapses apposed to synaptophysin-positive presynaptic terminals. The capacity of ErbB receptors to interact with PDZ-domain proteins at cell junctions is conserved from invertebrates to mammals. As discussed, the interactions found between receptor tyrosine kinases and MAGUKs at neuronal synapses may have important implications for activity-dependent plasticity.

    Proceedings of the National Academy of Sciences of the United States of America 2000;97;7;3596-601

  • A novel NE-dlg/SAP102-associated protein, p51-nedasin, related to the amidohydrolase superfamily, interferes with the association between NE-dlg/SAP102 and N-methyl-D-aspartate receptor.

    Kuwahara H, Araki N, Makino K, Masuko N, Honda S, Kaibuchi K, Fukunaga K, Miyamoto E, Ogawa M and Saya H

    Department of Tumor Genetics, Kumamoto University School of Medicine, 2-2-1 Honjo, Kumamoto 860-0811, Japan.

    The membrane-associated guanylate kinase proteins have been known to interact various membrane receptors with their N-terminal segments designated the PDZ domains and to cluster these receptors at the target site of the cell membrane. NE-dlg/SAP102, a neuronal and endocrine tissue-specific MAGUK family protein, was found to be expressed in both dendrites and cell bodies in neuronal cells. Although NE-dlg/SAP102 localized at dendrites was shown to interact with N-methyl-D-aspartate receptor 2B via the PDZ domains to compose postsynaptic density, the binding proteins existing in the cell body of the neuron are still unknown. Here we report the isolation of a novel NE-dlg/SAP102-associated protein, p51-nedasin. Nedasin has a significant homology with amidohydrolase superfamily proteins and shows identical sequences to a recently identified protein that has guanine aminohydrolase activity. Nedasin has four alternative splice variants (S, V1, V2, and V3) that exhibited different C-terminal structures. NE-dlg/SAP102 is shown to interact with only the S form of nedasin which is predominantly expressed in brain. The expression of nedasin in neuronal cells increases in parallel with the progress of synaptogenesis and is mainly detected in cell bodies where it co-localizes with NE-dlg/SAP102. Furthermore, nedasin interferes with the association between NE-dlg/SAP102 and NMDA receptor 2B in vitro. These findings suggest that alternative splicing of nedasin may play a role in the formation and/or structural change in synapses during neuronal development by modifying clustering of neurotransmitter receptors at the synaptic sites.

    The Journal of biological chemistry 1999;274;45;32204-14

  • Cypin: a cytosolic regulator of PSD-95 postsynaptic targeting.

    Firestein BL, Firestein BL, Brenman JE, Aoki C, Sanchez-Perez AM, El-Husseini AE and Bredt DS

    Department of Physiology, University of California, San Francisco 94143, USA.

    Postsynaptic density 95 (PSD-95/SAP-90) is a membrane associated guanylate kinase (GK) PDZ protein that scaffolds glutamate receptors and associated signaling networks at excitatory synapses. Affinity chromatography identifies cypin as a major PSD-95-binding protein in brain extracts. Cypin is homologous to a family of hydrolytic bacterial enzymes and shares some similarity with collapsin response mediator protein (CRMP), a cytoplasmic mediator of semaphorin III signalling. Cypin is discretely expressed in neurons and is polarized to basal membranes in intestinal epithelial cells. Overexpression of cypin in hippocampal neurons specifically perturbs postsynaptic trafficking of PSD-95 and SAP-102, an effect not produced by overexpression of other PDZ ligands. In fact, PSD-95 can induce postsynaptic clustering of an otherwise diffusely localized K+ channel, Kv1.4. By regulating postsynaptic protein sorting, cypin may influence synaptic development and plasticity.

    Funded by: NEI NIH HHS: R01-EY08055; NINDS NIH HHS: R01-NS36017

    Neuron 1999;24;3;659-72

  • Prediction of the coding sequences of unidentified human genes. XV. The complete sequences of 100 new cDNA clones from brain which code for large proteins in vitro.

    Nagase T, Ishikawa K, Kikuno R, Hirosawa M, Nomura N and Ohara O

    Kazusa DNA Research Institute, Kisarazu, Chiba, Japan. nagase@kazusa.or.jp

    In order to obtain information on the coding sequences of unidentified human genes, we newly determined the sequences of 100 cDNA clones of unknown human genes, which we named KIAA1193 to KIAA1292, from two sets of size-fractionated human adult and fetal brain cDNA libraries. The results of our particular strategy to select cDNA clones which have the potentiality of coding for large proteins in vitro revealed that the average sizes of the inserts and the corresponding open reading frames reached 5.2 kb and 2.8 kb (933 amino acid residues), respectively. By the computational analysis of the predicted amino acid sequences against the OWL and Pfam databases, 58 predicted gene products were classified into the following five functional categories: cell signaling/communication, cell structure/motility, nucleic acid management, protein management and metabolism. It was also found that 30 gene products had homologues in the public databases which were similar in sequence throughout almost their entire regions to the newly identified genes. The chromosomal loci of the genes were assigned by using human-rodent hybrid panels unless their mapping data were already available in the public databases. The expression profiles of the genes were studied in 10 human tissues, 8 brain regions, spinal cord, fetal brain and fetal liver by reverse transcription-coupled polymerase chain reaction, products of which were quantified by enzyme-linked immunosorbent assay.

    DNA research : an international journal for rapid publication of reports on genes and genomes 1999;6;5;337-45

  • Agonist-dependent interaction of the rat somatostatin receptor subtype 2 with cortactin-binding protein 1.

    Zitzer H, Richter D and Kreienkamp HJ

    Institut für Zellbiochemie und klinische Neurobiologie, Universität Hamburg, Martinistrasse 52, 20246 Hamburg, Germany.

    We report here an interaction between the C terminus of the rat somatostatin receptor subtype 2 (SSTR2) and a protein that has recently been identified as cortactin-binding protein 1 (CortBP1). Interaction is mediated by the PDZ (PSD-95/discs large/ZO-1) domain of CortBP1. As shown by in situ hybridization, SSTR2 and cortactin-binding protein are coexpressed in the rat brain. The association between SSTR2 and the PDZ-domain of CortBP1 was verified by overlay assays and by coprecipitation after transfection in human embryonic kidney (HEK) cells. Analysis by confocal microscopy indicates that CortBP1 is distributed diffusely throughout the cytosol in transfected cells and that it becomes concentrated at the plasma membrane when SSTR2 is present. This process is largely increased when the receptor is stimulated by somatostatin; as CortBP1 interacts with the C terminus of SSTR2, our data suggest that the binding of agonist to the receptor increase the accessibility of the receptor C terminus to the PDZ domain of CortBP1. Our data for the first time establish a link between a G-protein coupled receptor and constituents of the cytoskeleton.

    The Journal of biological chemistry 1999;274;26;18153-6

  • Interaction of NE-dlg/SAP102, a neuronal and endocrine tissue-specific membrane-associated guanylate kinase protein, with calmodulin and PSD-95/SAP90. A possible regulatory role in molecular clustering at synaptic sites.

    Masuko N, Makino K, Kuwahara H, Fukunaga K, Sudo T, Araki N, Yamamoto H, Yamada Y, Miyamoto E and Saya H

    Department of Tumor Genetics and Biology, Kumamoto University School of Medicine, 2-2-1, Honjo, Kumamoto 860-0811, Japan.

    NE-dlg/SAP102, a neuronal and endocrine tissue-specific membrane-associated guanylate kinase family protein, is known to bind to C-terminal ends of N-methyl-D-aspartate receptor 2B (NR2B) through its PDZ (PSD-95/Dlg/ZO-1) domains. NE-dlg/SAP102 and NR2B colocalize at synaptic sites in cultured rat hippocampal neurons, and their expressions increase in parallel with the onset of synaptogenesis. We have identified that NE-dlg/SAP102 interacts with calmodulin in a Ca2+-dependent manner. The binding site for calmodulin has been determined to lie at the putative basic alpha-helix region located around the src homology 3 (SH3) domain of NE-dlg/SAP102. Using a surface plasmon resonance measurement system, we detected specific binding of recombinant NE-dlg/SAP102 to the immobilized calmodulin with a Kd value of 44 nM. However, the binding of Ca2+/calmodulin to NE-dlg/SAP102 did not modulate the interaction between PDZ domains of NE-dlg/SAP102 and the C-terminal end of rat NR2B. We have also identified that the region near the calmodulin binding site of NE-dlg/SAP102 interacts with the GUK-like domain of PSD-95/SAP90 by two-hybrid screening. Pull down assay revealed that NE-dlg/SAP102 can interact with PSD-95/SAP90 in the presence of both Ca2+ and calmodulin. These findings suggest that the Ca2+/calmodulin modulates interaction of neuronal membrane-associated guanylate kinase proteins and regulates clustering of neurotransmitter receptors at central synapses.

    The Journal of biological chemistry 1999;274;9;5782-90

  • SAP90 binds and clusters kainate receptors causing incomplete desensitization.

    Garcia EP, Mehta S, Blair LA, Wells DG, Shang J, Fukushima T, Fallon JR, Garner CC and Marshall J

    Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, Rhode Island 02912, USA.

    The mechanism of kainate receptor targeting and clustering is still unresolved. Here, we demonstrate that members of the SAP90/PSD-95 family colocalize and associate with kainate receptors. SAP90 and SAP102 coimmunoprecipitate with both KA2 and GluR6, but only SAP97 coimmunoprecipitates with GluR6. Similar to NMDA receptors, GluR6 clustering is mediated by the interaction of its C-terminal amino acid sequence, ETMA, with the PDZ1 domain of SAP90. In contrast, the KA2 C-terminal region binds to, and is clustered by, the SH3 and GK domains of SAP90. Finally, we show that SAP90 coexpressed with GluR6 or GluR6/KA2 receptors alters receptor function by reducing desensitization. These studies suggest that the organization and electrophysiological properties of synaptic kainate receptors are modified by association with members of the SAP90/PSD-95 family.

    Funded by: NICHD NIH HHS: R01 HD023924, R01 HD052083; NINDS NIH HHS: R29 NS 33914-02

    Neuron 1998;21;4;727-39

  • A tripartite protein complex with the potential to couple synaptic vesicle exocytosis to cell adhesion in brain.

    Butz S, Okamoto M and Südhof TC

    Center for Basic Neuroscience, Department of Molecular Genetics, Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center at Dallas, 75235, USA.

    We identify a complex of three proteins in brain that has the potential to couple synaptic vesicle exocytosis to neuronal cell adhesion. The three proteins are: (1) CASK, a protein related to MAGUKs (membrane-associated guanylate kinases); (2) Mint1, a putative vesicular trafficking protein; and (3) Veli1, -2, and -3, vertebrate homologs of C. elegans LIN-7. CASK, Mint1, and Velis form a tight, salt-resistant complex that can be readily isolated. CASK, Mint1, and Velis contain PDZ domains in addition to other modules. However, no PDZ domains are involved in complex formation, leaving them free to recruit cell adhesion molecules, receptors, and channels to the complex. We propose that the tripartite complex acts as a nucleation site for the assembly of proteins involved in synaptic vesicle exocytosis and synaptic junctions.

    Funded by: NIMH NIH HHS: R01-MH52804

    Cell 1998;94;6;773-82

  • DLG3, the gene encoding human neuroendocrine Dlg (NE-Dlg), is located within the 1.8-Mb dystonia-parkinsonism region at Xq13.1.

    Stathakis DG, Lee D and Bryant PJ

    Developmental Biology Center, University of California, Irvine 92697-2275, USA. dgstatha@uci.edu

    Neuroendocrine-Dlg (NE-Dlg) is a member of the discs-large-related (DLG) subfamily of the membrane-associated guanylate kinase-related protein family. Based on evidence from model systems, this protein appears to be critical for synaptogenesis, acting as a site-specific organizational center for integral membrane proteins and their downstream signaling molecules associated with the cytoskeleton. NE-Dlg also directly interacts with the colorectal tumor suppressor adenomatous polyposis coli, suggesting that it may play a role in regulating cell proliferation in epithelial cells. To explore the genetic control of NE-Dlg, we developed a physical map of the chromosome region containing DLG3, the locus encoding NE-Dlg. Using human-hamster radiation hybrid mapping panels, we mapped DLG3 to Xq13.1 and established a sequence-tagged site marker map of the surrounding region. We then developed a yeast artificial chromosome (YAC) contig for this region. Encompassing approximately 2.0 Mb contained within five overlapping YACs, this contig also includes the dystonia-parkinsonism syndrome (DYT3) locus. The close proximity of DLG3 to the DYT3 region suggests that the gene encoding NE-Dlg is a candidate locus for this neurological disorder.

    Funded by: NCI NIH HHS: P01 CA66263, P30 CA62203

    Genomics 1998;49;2;310-3

  • SynGAP: a synaptic RasGAP that associates with the PSD-95/SAP90 protein family.

    Kim JH, Liao D, Lau LF and Huganir RL

    Department of Neuroscience, Howard Huges Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.

    The PSD-95/SAP90 family of proteins has recently been implicated in the organization of synaptic structure. Here, we describe the isolation of a novel Ras-GTPase activating protein, SynGAP, that interacts with the PDZ domains of PSD-95 and SAP102 in vitro and in vivo. SynGAP is selectively expressed in brain and is highly enriched at excitatory synapses, where it is present in a large macromolecular complex with PSD-95 and the NMDA receptor. SynGAP stimulates the GTPase activity of Ras, suggesting that it negatively regulates Ras activity at excitatory synapses. Ras signaling at the postsynaptic membrane may be involved in the modulation of excitatory synaptic transmission by NMDA receptors and neurotrophins. These results indicate that SynGAP may play an important role in the modulation of synaptic plasticity.

    Funded by: NINDS NIH HHS: T32NS07368

    Neuron 1998;20;4;683-91

  • Binding of neuroligins to PSD-95.

    Irie M, Hata Y, Takeuchi M, Ichtchenko K, Toyoda A, Hirao K, Takai Y, Rosahl TW and Südhof TC

    Takai Biotimer Project, ERATO, Japan Science and Technology Corporation, 2-2-10, Murotani, Nishi-ku, Kobe, 651-22, Japan.

    PSD-95 is a component of postsynaptic densities in central synapses. It contains three PDZ domains that localize N-methyl-D-aspartate receptor subunit 2 (NMDA2 receptor) and K+ channels to synapses. In mouse forebrain, PSD-95 bound to the cytoplasmic COOH-termini of neuroligins, which are neuronal cell adhesion molecules that interact with beta-neurexins and form intercellular junctions. Neuroligins bind to the third PDZ domain of PSD-95, whereas NMDA2 receptors and K+ channels interact with the first and second PDZ domains. Thus different PDZ domains of PSD-95 are specialized for distinct functions. PSD-95 may recruit ion channels and neurotransmitter receptors to intercellular junctions formed between neurons by neuroligins and beta-neurexins.

    Funded by: NIMH NIH HHS: R01-MH52804

    Science (New York, N.Y.) 1997;277;5331;1511-5

  • Cloning and characterization of NE-dlg: a novel human homolog of the Drosophila discs large (dlg) tumor suppressor protein interacts with the APC protein.

    Makino K, Kuwahara H, Masuko N, Nishiyama Y, Morisaki T, Sasaki J, Nakao M, Kuwano A, Nakata M, Ushio Y and Saya H

    Department of Tumor Genetics and Biology, Kumamoto University School of Medicine, Honjo Kumamoto, Japan.

    We have cloned a cDNA for a novel human homolog of the Drosophila discs large (dig) tumor suppressor protein, termed NE-dlg (neuronal and endocrine dig). Northern blot analysis revealed that the gene is highly expressed in neuronal and endocrine tissues. Fluorescence in situ hybridization (FISH) and radiation hybrid mapping studies localized the NE-dlg gene to chromosome Xq13. We also found that the NE-dlg gene encoded a 100 kDa protein. Immunolocalization studies using an NE-dlg antibody showed that the protein tended to be expressed in non-proliferating cells, such as neurons, cells in Langerhans islets of the pancreas, myocytes of the heart muscles, and the prickle and functional layer cells of the esophageal epithelium. Proliferative cells, including various cultured cancer cell lines and basal cells in the esophageal epithelium, showed little expression of the NE-dlg protein. In addition, yeast two-hybrid screening and in vitro binding assays revealed that the NE-dlg interacted with the carboxyl-terminal region of the APC tumor suppressor protein. These data suggest that NE-dlg negatively regulates cell proliferation through its interaction with the APC protein.

    Oncogene 1997;14;20;2425-33

  • SAPAPs. A family of PSD-95/SAP90-associated proteins localized at postsynaptic density.

    Takeuchi M, Hata Y, Hirao K, Toyoda A, Irie M and Takai Y

    Takai Biotimer Project, ERATO, Japan Science and Technology Corporation, c/o JCR Pharmaceuticals Co., Ltd., 2-2-10 Murotani, Nishi-ku, Kobe 651-22, Japan.

    PSD-95/SAP90 is a member of membrane-associated guanylate kinases localized at postsynaptic density (PSD) in neuronal cells. Membrane-associated guanylate kinases are a family of signaling molecules expressed at various submembrane domains which have the PDZ (DHR) domains, the SH3 domain, and the guanylate kinase domain. PSD-95/SAP90 interacts with N-methyl-D-aspartate receptors 2A/B, Shaker-type potassium channels, and brain nitric oxide synthase through the PDZ (DHR) domains and clusters these molecules at synaptic junctions. However, neither the function of the SH3 domain or the guanylate kinase domain of PSD-95/SAP90, nor the protein interacting with these domains has been identified. We have isolated here a novel protein family consisting of at least four members which specifically interact with PSD-95/SAP90 and its related proteins through the guanylate kinase domain, and named these proteins SAPAPs (SAP90/PSD-95-Associated Proteins). SAPAPs are specifically expressed in neuronal cells and enriched in the PSD fraction. SAPAPs induce the enrichment of PSD-95/SAP90 to the plasma membrane in transfected cells. Thus, SAPAPs may have a potential activity to maintain the structure of PSD by concentrating its components to the membrane area.

    The Journal of biological chemistry 1997;272;18;11943-51

  • Interaction of the N-methyl-D-aspartate receptor complex with a novel synapse-associated protein, SAP102.

    Lau LF, Mammen A, Ehlers MD, Kindler S, Chung WJ, Garner CC and Huganir RL

    Department of Neuroscience, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2185, USA.

    Ionotropic glutamate receptors are known to cluster at high concentration on the postsynaptic membrane of excitatory synapses, but the mechanism by which this occurs is poorly understood. Studies on the neuromuscular junction and central inhibitory synapses suggest that clustering of neurotransmitter receptors requires its interaction with a cytoplasmic protein. Recently, in vitro studies have shown that members of the N-methyl--aspartate (NMDA) class of glutamate receptors interact with a synapse-associated protein, SAP90 (PSD-95). However, evidence for the in vivo interaction of NMDA receptors with SAPs is still lacking. In the present study, we demonstrate the specific interaction between SAP102, a novel synapse-associated protein, and the NMDA receptor complex from the rat cortical synaptic plasma membranes using co-immunoprecipitation techniques. No association was observed between SAP102 and GluR1, a member of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate class of glutamate receptors. To identify the domain on the NMDA receptor responsible for this interaction, we constructed hexahistidine fusion proteins from different regions of the NR1a and NR2 subunits of the NMDA receptor. Immunoblot overlay experiments showed that while the C-terminal domain of the NR2 subunit displayed strong binding, the NR1a intracellular C-terminal tail did not interact with SAP102. The site of interaction was more precisely located to the last 20 amino acids of the NR2 subunit as indicated by the interaction of the synthetic peptide with SAP102. In summary, we demonstrate here for the first time an in vivo interaction between the native NMDA receptor complex and a synapse-associated protein. These results suggest that SAP102 may play an important role in NMDA receptor clustering and immobilization at excitatory synapses.

    The Journal of biological chemistry 1996;271;35;21622-8

  • SAP102, a novel postsynaptic protein that interacts with NMDA receptor complexes in vivo.

    Müller BM, Kistner U, Kindler S, Chung WJ, Kuhlendahl S, Fenster SD, Lau LF, Veh RW, Huganir RL, Gundelfinger ED and Garner CC

    Center for Molecular Neurobiology, University of Hamburg, Federal Republic of Germany.

    Synapse-associated proteins (SAPs) are constituents of the pre- and postsynaptic submembraneous cytomatrix. Here, we present SAP102, a novel 102kDa SAP detected in dendritic shafts and spines of asymmetric type 1 synapses. SAP102 is enriched in preparations of synaptic junctions, where it biochemically behaves as a component of the cortical cytoskeleton. Antibodies directed against NMDA receptors coimmunoprecipitate SAP102 from rat brain synaptosomes. Recombinant proteins containing the carboxy-terminal tail of NMDA receptor subunit NR2B interact with SAP102 from rat brain homogenates. All three PDZ domains in SAP102 bind the cytoplasmic tail of NR2B in vitro. These data represent direct evidence that in vivo SAP102 is involved in linking NMDA receptors to the submembraneous cytomatrix associated with postsynaptic densities at excitatory synapses.

    Funded by: NICHD NIH HHS: P50 HD32901

    Neuron 1996;17;2;255-65

OMIM - other

Gene lists (9)

Gene List Source Species Name Description Gene count
L00000009 G2C Homo sapiens Human PSD Human orthologues of mouse PSD adapted from Collins et al (2006) 1080
L00000015 G2C Homo sapiens Human NRC Human orthologues of mouse NRC adapted from Collins et al (2006) 186
L00000016 G2C Homo sapiens Human PSP Human orthologues of mouse PSP adapted from Collins et al (2006) 1121
L00000032 G2C Homo sapiens Pocklington H1 Human orthologues of cluster 1 (mouse) from Pocklington et al (2006) 21
L00000049 G2C Homo sapiens TAP-PSD-95-CORE TAP-PSD-95 pull-down core list (ortho) 120
L00000059 G2C Homo sapiens BAYES-COLLINS-HUMAN-PSD-CONSENSUS Human cortex PSD consensus 748
L00000061 G2C Homo sapiens BAYES-COLLINS-MOUSE-PSD-CONSENSUS Mouse cortex PSD consensus (ortho) 984
L00000069 G2C Homo sapiens BAYES-COLLINS-HUMAN-PSD-FULL Human cortex biopsy PSD full list 1461
L00000071 G2C Homo sapiens BAYES-COLLINS-MOUSE-PSD-FULL Mouse cortex PSD full list (ortho) 1556
© G2C 2014. The Genes to Cognition Programme received funding from The Wellcome Trust and the EU FP7 Framework Programmes:
EUROSPIN (FP7-HEALTH-241498), SynSys (FP7-HEALTH-242167) and GENCODYS (FP7-HEALTH-241995).

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