G2Cdb::Gene report

Gene id
Gene symbol
Homo sapiens
Kell blood group, metallo-endopeptidase
G00000316 (Mus musculus)

Databases (8)

Curated Gene
OTTHUMG00000023169 (Vega human gene)
ENSG00000197993 (Ensembl human gene)
3792 (Entrez Gene)
652 (G2Cdb plasticity & disease)
KEL (GeneCards)
110900 (OMIM)
Marker Symbol
HGNC:6308 (HGNC)
Protein Sequence
P23276 (UniProt)

Synonyms (2)

  • CD238
  • ECE3

Literature (28)

Pubmed - other

  • Two novel null alleles of the KEL gene detected in two Chinese women with the K(null) phenotype.

    Yang Y, Wang L, Wang C, Chen H, Guo Z, Zhang Y and Zhu Z

    Shanghai Blood Center, Shanghai, China 200051. yangyinghla@yahoo.com.cn

    In screening 87665 unrelated healthy blood donors in China, serology studies resulted in the detection of two K(0) probands, both female. To explore the molecular basis of the K(null) phenotype in the Chinese population, genomic DNA, total RNA, and reticulocyte RNA were subsequently prepared from the two probands, five family members of proband 1, four unrelated normal controls, and one unrelated KEL1 control. Nucleic acids were analyzed for the KEL gene by DNA and RNA sequencing, while antigens were analyzed by flow cytometry with BRIC18, BRIC68, anti-k, and anti-Kp(b). Two novel K(null) alleles were identified in both probands: in exon 3, 185insT (Ser62Phe and a premature stop codon in exon 4, GenBank accession number, EF208900), and in exon 7, 715G>T (Glu239Stop, GenBank accession number EF208901). Alternative splicing patterns were observed in RNA obtained from whole blood versus from a reticulocyte fraction. Our study identified these two novel K(null) alleles resulting in the K(null) phenotype, the frequency of the K(null) phenotype amongst Chinese mainlanders is only 0.00228%.

    Transfusion medicine (Oxford, England) 2009;19;5;235-44

  • A novel KEL*1,3 allele with weak Kell antigen expression confirming the cis-modifier effect of KEL3.

    Körmöczi GF, Scharberg EA and Gassner C

    Department of Blood Group Serology and Transfusion Medicine, Medical University of Vienna, Währinger Gürtel 18-20, Vienna, Austria. guenther.koermoeczi@meduniwien.ac.at

    Background: KEL1 (K) is the most immunogenic red blood cell antigen of the Kell blood group system. The frequently occurring anti-KEL1 alloantibodies may cause hemolytic transfusion reactions as well as severe hemolytic disease of the fetus and newborn. So far, reports on weak KEL phenotypes are scarce.

    Blood samples of two unrelated Central European propositi with faint reactions in routine KEL1 typing were analyzed by extended serologic phenotyping, flow cytometry, genotyping by polymerase chain reaction with sequence-specific priming, and genomic DNA sequencing of separated parental KEL alleles.

    Results: Both propositi exhibited an unusual KEL:1,2,3,4 phenotype: markedly weakened and negative reactions were observed in serologic KEL1 typing in gel and tube technique, respectively. No KEL1 epitope loss was detected using five different monoclonal anti-KEL1 reagents. KEL genotyping confirmed KEL*1/2 and KEL*3/4 (Kpa/Kpb) heterozygosity of both individuals. Importantly, DNA sequencing of the two separated parental alleles of both propositi revealed a KEL*1-specific coding nucleotide T578 and a KEL*3-specific T841 on the same allele. This novel KEL*1,3 (KKpa)allele was associated with an approximately 80 percent reduction in KEL1 expression, compared to KEL:1,2,-3,4 controls. The low KEL1 density was attributed to acis-modifier effect of KEL3, so far only reported in association with weakened expression of KEL2 (k).

    Conclusion: This is the first description of the KEL*1,3 allele encoding KEL1 and KEL3 on the same molecule. In individuals with weakened KEL1 because of KEL3 in cis, very sensitive serologic or molecular genetic techniques may be required for reliable Kell typing.

    Transfusion 2009;49;4;733-9

  • Introduction of a real-time-based blood-group genotyping approach.

    Polin H, Danzer M, Pröll J, Hofer K, Heilinger U, Zopf A and Gabriel C

    Red Cross Transfusion Service of Upper Austria, Linz, Austria. helene.polin@blutz.o.redcross.or.at

    Genotyping may be applied for rare blood group polymorphisms in a high-throughput mode as well for the molecular determination of blood groups due to unclear serological results.

    We developed and validated a DNA typing method for the determination of KEL1/2, JK1/2, FY1/2, FY0, MNS1/2, MNS3/4, DO1/2, CO1/2 and LU1/2 alleles using a melting curve analysis downstream from a fully automated DNA extraction. All assays were validated in terms of specificity, sensitivity, assay variability and robustness. The usability was proven by a batch of 200 blood samples with partially known phenotype.

    Results: Assays for all blood groups were within the range of specificity (100%), assay variability and robustness (coefficient of variance < 3%). Genotypes of 200 random platelet donors were fully consistent with existing phenotype data. The obtained genotype distribution is in complete concordance with existing data for the European population underlined by a complete absence of CO2 homozygous donors and the FY0 allele among the cohort.

    Conclusion: We introduce an approach for blood group genotyping of particular samples or gene loci in glass capillary format and for medium-throughput analysis in 96/384-well format. The advantages of this real-time polymerase chain reaction method are its automation potential, the flexibility regarding hardware and the rapid cycling time.

    Vox sanguinis 2008;95;2;125-30

  • Blood group genotyping for Jk(a)/Jk(b), Fy(a)/Fy(b), S/s, K/k, Kp(a)/Kp(b), Js(a)/Js(b), Co(a)/Co(b), and Lu(a)/Lu(b) with microarray beads.

    Karpasitou K, Drago F, Crespiatico L, Paccapelo C, Truglio F, Frison S, Scalamogna M and Poli F

    Regenerative Medicine Department, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli, Regina Elena, Milan, Italy.

    Background: Traditionally, blood group typing has been performed with serologic techniques, the classical method being the hemagglutination test. Serotyping, however, may present important limitations such as scarce availability of rare antisera, typing of recently transfused patients, and those with a positive direct antiglobulin test. Consequently, serologic tests are being complemented with molecular methods. The aim of this study was to develop a low-cost, high-throughput method for large-scale genotyping of red blood cells (RBCs).

    Single-nucleotide polymorphisms associated with some clinically important blood group antigens, as well as with certain rare blood antigens, were evaluated: Jk(a)/Jk(b), Fy(a)/Fy(b), S/s, K/k, Kp(a)/Kp(b), Js(a)/Js(b), Co(a)/Co(b), and Lu(a)/Lu(b). Polymerase chain reaction (PCR)-amplified targets were detected by direct hybridization to microspheres coupled to allele-specific oligonucleotides. Cutoff values for each genotype were established with phenotyped and/or genotyped samples.

    Results: The method was validated with a blind panel of 92 blood donor samples. The results were fully concordant with those provided by hemagglutination assays and/or sequence-specific primer (SSP)-PCR. The method was subsequently evaluated with approximately 800 blood donor and patient samples.

    Conclusion: This study presents a flexible, quick, and economical method for complete genotyping of large donor cohorts for RBC alleles.

    Transfusion 2008;48;3;505-12

  • The Kell and XK proteins of the Kell blood group are not co-expressed in the central nervous system.

    Clapéron A, Hattab C, Armand V, Trottier S, Bertrand O and Ouimet T

    INSERM U573, Centre Paul Broca, 2ter rue d'Alésia, 75014 Paris, France.

    The Kell blood group is constituted by two covalently linked antigens at the surface of red blood cells, Kell and Kx. Whereas Kell is a metalloprotease with demonstrated in vitro enzymatic activity, the role of Kx thereon, and/or alone, remains unknown, although its absence is linked to the McLeod syndrome, a neuroacanthocytosis. In the central nervous system, the expression of Kell and XK has been suggested, but their expression patterns remain uncharacterized, as are the post-translational pathogenic mechanisms involved in the development of the McLeod syndrome. The distributions of Kell and XK were thus studied by in situ hybridization as well as immunohistochemistry in rodent and human brain. The results reveal an independent localization of the two constituents of the Kell blood group, XK (Kx) being expressed throughout this tissue, whereas Kell expression is restricted to red blood cells in cerebral vessels. The XK protein is shown to be neuronal, located mainly in intracellular compartments, suggesting a cell specific trafficking pattern, possibly associated with specific physiological functions.

    Brain research 2007;1147;12-24

  • Endothelin-3-converting enzyme activity of the KEL1 and KEL6 phenotypes of the Kell blood group system.

    Sha Q, Redman CM and Lee S

    Lindsley F. Kimball Research Institute of the New York Blood Center, 310 East 67th Street, New York, NY 10021, USA.

    The Kell blood group protein is a metalloendopeptidase that preferentially cleaves a Trp(21)-Ile(22) bond of big endothelin-3 producing bioactive endothelin-3. Kell is a polymorphic protein, and 25 different phenotypes, because of point mutations resulting in single amino acid substitutions, have been described. It was recently reported that a recombinant form of KEL1 (K, K1) phenotype, expressed in K562 and HEK293 cells, had no endothelin-3-converting activity, in contrast to the common KEL2 (k, K2) phenotype. We demonstrate that KEL1 red blood cells and also a soluble recombinant form of KEL1 protein (s-Kell KEL1) have similar enzymatic activity as the common Kell phenotype. In addition we show that KEL6 red blood cells, which are more prevalent in persons of African heritage than in Caucasians also have endothelin-3-converting enzyme activity and that the recombinant soluble form of KEL6 protein (s-Kell KEL6) has similar K(m) values as the wild-type.

    Funded by: NHLBI NIH HHS: HL 54459, R01 HL 075716

    The Journal of biological chemistry 2006;281;11;7180-2

  • Towards a proteome-scale map of the human protein-protein interaction network.

    Rual JF, Venkatesan K, Hao T, Hirozane-Kishikawa T, Dricot A, Li N, Berriz GF, Gibbons FD, Dreze M, Ayivi-Guedehoussou N, Klitgord N, Simon C, Boxem M, Milstein S, Rosenberg J, Goldberg DS, Zhang LV, Wong SL, Franklin G, Li S, Albala JS, Lim J, Fraughton C, Llamosas E, Cevik S, Bex C, Lamesch P, Sikorski RS, Vandenhaute J, Zoghbi HY, Smolyar A, Bosak S, Sequerra R, Doucette-Stamm L, Cusick ME, Hill DE, Roth FP and Vidal M

    Center for Cancer Systems Biology and Department of Cancer Biology, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston, Massachusetts 02115, USA.

    Systematic mapping of protein-protein interactions, or 'interactome' mapping, was initiated in model organisms, starting with defined biological processes and then expanding to the scale of the proteome. Although far from complete, such maps have revealed global topological and dynamic features of interactome networks that relate to known biological properties, suggesting that a human interactome map will provide insight into development and disease mechanisms at a systems level. Here we describe an initial version of a proteome-scale map of human binary protein-protein interactions. Using a stringent, high-throughput yeast two-hybrid system, we tested pairwise interactions among the products of approximately 8,100 currently available Gateway-cloned open reading frames and detected approximately 2,800 interactions. This data set, called CCSB-HI1, has a verification rate of approximately 78% as revealed by an independent co-affinity purification assay, and correlates significantly with other biological attributes. The CCSB-HI1 data set increases by approximately 70% the set of available binary interactions within the tested space and reveals more than 300 new connections to over 100 disease-associated proteins. This work represents an important step towards a systematic and comprehensive human interactome project.

    Funded by: NCI NIH HHS: R33 CA132073; NHGRI NIH HHS: P50 HG004233, R01 HG001715, RC4 HG006066, U01 HG001715; NHLBI NIH HHS: U01 HL098166

    Nature 2005;437;7062;1173-8

  • The Kell protein of the common K2 phenotype is a catalytically active metalloprotease, whereas the rare Kell K1 antigen is inactive. Identification of novel substrates for the Kell protein.

    Clapéron A, Rose C, Gane P, Collec E, Bertrand O and Ouimet T

    INSERM U573, 75014 Paris, France.

    The Kell blood group is a highly polymorphic system containing over 20 different antigens borne by the protein Kell, a 93-kDa type II glycoprotein that displays high sequence homology with members of the M13 family of zinc-dependent metalloproteases whose prototypical member is neprilysin. Kell K1 is an antigen expressed in 9% of the Caucasian population, characterized by a point mutation (T193M) of the Kell K2 antigen, and located within a putative N-glycosylation consensus sequence. Recently, a recombinant, non-physiological, soluble form of Kell was shown to cleave Big ET-3 to produce the mature vasoconstrictive peptide. To better characterize the enzymatic activity of the Kell protein and the possible differences introduced by antigenic point mutations affecting post-translational processing, the membrane-bound forms of the Kell K1 and Kell K2 antigens were expressed either in K562 cells, an erythroid cell line, or in HEK293 cells, a non-erythroid system, and their pharmacological profiles and enzymatic specificities toward synthetic and natural peptides were evaluated. Results presented herein reveal that the two antigens possess considerable differences in their enzymatic activities, although not in their trafficking pattern. Indeed, although both antigens are expressed at the cell surface, Kell K1 protein is shown to be inactive, whereas the Kell K2 antigen binds neprilysin inhibitory compounds such as phosphoramidon and thiorphan with high affinity, cleaves the precursors of the endothelin peptides, and inactivates members of the tachykinin family with enzymatic properties resembling those of other members of the M13 family of metalloproteases to which it belongs.

    The Journal of biological chemistry 2005;280;22;21272-83

  • The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).

    Gerhard DS, Wagner L, Feingold EA, Shenmen CM, Grouse LH, Schuler G, Klein SL, Old S, Rasooly R, Good P, Guyer M, Peck AM, Derge JG, Lipman D, Collins FS, Jang W, Sherry S, Feolo M, Misquitta L, Lee E, Rotmistrovsky K, Greenhut SF, Schaefer CF, Buetow K, Bonner TI, Haussler D, Kent J, Kiekhaus M, Furey T, Brent M, Prange C, Schreiber K, Shapiro N, Bhat NK, Hopkins RF, Hsie F, Driscoll T, Soares MB, Casavant TL, Scheetz TE, Brown-stein MJ, Usdin TB, Toshiyuki S, Carninci P, Piao Y, Dudekula DB, Ko MS, Kawakami K, Suzuki Y, Sugano S, Gruber CE, Smith MR, Simmons B, Moore T, Waterman R, Johnson SL, Ruan Y, Wei CL, Mathavan S, Gunaratne PH, Wu J, Garcia AM, Hulyk SW, Fuh E, Yuan Y, Sneed A, Kowis C, Hodgson A, Muzny DM, McPherson J, Gibbs RA, Fahey J, Helton E, Ketteman M, Madan A, Rodrigues S, Sanchez A, Whiting M, Madari A, Young AC, Wetherby KD, Granite SJ, Kwong PN, Brinkley CP, Pearson RL, Bouffard GG, Blakesly RW, Green ED, Dickson MC, Rodriguez AC, Grimwood J, Schmutz J, Myers RM, Butterfield YS, Griffith M, Griffith OL, Krzywinski MI, Liao N, Morin R, Morrin R, Palmquist D, Petrescu AS, Skalska U, Smailus DE, Stott JM, Schnerch A, Schein JE, Jones SJ, Holt RA, Baross A, Marra MA, Clifton S, Makowski KA, Bosak S, Malek J and MGC Project Team

    The National Institutes of Health's Mammalian Gene Collection (MGC) project was designed to generate and sequence a publicly accessible cDNA resource containing a complete open reading frame (ORF) for every human and mouse gene. The project initially used a random strategy to select clones from a large number of cDNA libraries from diverse tissues. Candidate clones were chosen based on 5'-EST sequences, and then fully sequenced to high accuracy and analyzed by algorithms developed for this project. Currently, more than 11,000 human and 10,000 mouse genes are represented in MGC by at least one clone with a full ORF. The random selection approach is now reaching a saturation point, and a transition to protocols targeted at the missing transcripts is now required to complete the mouse and human collections. Comparison of the sequence of the MGC clones to reference genome sequences reveals that most cDNA clones are of very high sequence quality, although it is likely that some cDNAs may carry missense variants as a consequence of experimental artifact, such as PCR, cloning, or reverse transcriptase errors. Recently, a rat cDNA component was added to the project, and ongoing frog (Xenopus) and zebrafish (Danio) cDNA projects were expanded to take advantage of the high-throughput MGC pipeline.

    Funded by: PHS HHS: N01-C0-12400

    Genome research 2004;14;10B;2121-7

  • Genetic characterization of the population of Grande Comore Island (Njazidja) according to major blood groups.

    Chiaroni J, Touinssi M, Frassati C, Degioanni A, Gibert M, Reviron D, Mercier P and Boëtsch G

    Laboratoire Polymorphisme Génétique Humain, Etablissement Français du Sang Alpes-Méditerranée, 13005 Marseille, France.

    The Comorian population is historically considered a blend of influences from African Bantus, Arabs, and possibly Austronesians. In this study we present the first genetic data on the current Comorian population. Serologic analysis of the six major blood group systems (ABO, RH, KEL, FY, JK, and MNS) was performed on 164 individuals from Grande Comore Island (Njazidja). In addition, Duffy genotypes were determined by polymerase chain reaction using allele-specific primers. Our findings establish a high frequency of the Fy(a- b-) phenotype (86%), presenting the same genetic background as in sub-Saharan Africa. Analysis of genetic frequencies, distances, and admixture with other populations indicates that African Bantus made the main contribution to the gene pool (73.2%+/-15.5%). The Arab contribution from the Arabian peninsula was smaller (24.2%+/-7%) and the Indonesian contribution was minor (2.6%+/-9%). The major Bantu contribution was commensurate with the Bantu cultural influence. The contribution from the Arabian peninsula seemed in relation to its permeating religious and linguistic influence. As with the language, the Indonesian contribution to the Comorian gene pool was small. These results are in agreement with historical, sociological, and linguistic data.

    Human biology 2004;76;4;527-41

  • Active amino acids of the Kell blood group protein and model of the ectodomain based on the structure of neutral endopeptidase 24.11.

    Lee S, Debnath AK and Redman CM

    Lindsley F. Kimball Research Institute, New York Blood Center, 310 E 67th St, New York, NY 10021, USA. solee@nybloodcenter.org

    In addition to its importance in transfusion, Kell protein is a member of the M13 family of zinc endopeptidases and functions as an endothelin-3-converting enzyme. To obtain information on the structure of Kell protein we built a model based on the crystal structure of the ectodomain of neutral endopeptidase 24.11 (NEP). Similar to NEP, the Kell protein has 2 globular domains consisting mostly of alpha-helical segments. The domain situated closest to the membrane contains both the N- and C-terminal sequences and the enzyme-active site. The outer domain contains all of the amino acids whose substitutions lead to different Kell blood group phenotypes. In the model, the zinc peptidase inhibitor, phosphoramidon, was docked in the active site. Site-directed mutagenesis of amino acids in the active site was performed and the enzymatic activities of expressed mutant Kell proteins analyzed and compared with NEP. Our studies indicate that Kell and NEP use the same homologous amino acids in the coordination of zinc and in peptide hydrolysis. However, Kell uses different amino acids than NEP in substrate binding and appears to have more flexibility in the composition of amino acids allowed in the active site.

    Funded by: NHLBI NIH HHS: HL54459

    Blood 2003;102;8;3028-34

  • Molecular defects underlying the Kell null phenotype.

    Lee S, Russo DC, Reiner AP, Lee JH, Sy MY, Telen MJ, Judd WJ, Simon P, Rodrigues MJ, Chabert T, Poole J, Jovanovic-Srzentic S, Levene C, Yahalom V and Redman CM

    Lindsley F. Kimball Research Institute of the New York Blood Center, New York, New York 10021, USA.

    Expression of the Kell blood group system is dependent on two proteins, Kell and XK, that are linked by a single disulfide bond. Kell, a type II membrane glycoprotein, is a zinc endopeptidase, while XK, which has 10 transmembrane domains, is a putative membrane transporter. A rare phenotype termed Kell null (Ko) is characterized by the absence of Kell protein and Kell antigens from the red cell membrane and diminished amounts of XK protein. We determined the molecular basis of eight unrelated persons with Ko phenotypes by sequencing the coding and the intron-exon splice regions of KEL and, in some cases, analysis of mRNA transcripts and expression of mutants on the cell surface of transfected cells. Six subjects were homozygous: four with premature stop codons, one with a 5' splice site mutation, G to A, in intron 3, and one with an amino acid substitution (S676N) in exon 18. Two Ko persons with premature stop codons had identical mutations in exon 4 (R128Stop), another had a different mutation in exon 4 (C83Stop), and the fourth had a stop codon in exon 9 (Q348Stop). Two Ko persons were heterozygous for two mutations. One had a 5' splice site mutation (G to A) in intron 3 of one allele that caused aberrant splicing and exon skipping, and the other allele had an amino acid substitution in exon 10 (S363N). The other heterozygote had the same amino acid substitution in exon 10 (S363N) in one allele and a premature stop codon in exon 6 (R192Stop) in the other allele. The S363N and S676N mutants, expressed in 293T cells, were retained in a pre-Golgi compartment and were not transported to the cell surface, indicating that these mutations inhibit trafficking. We conclude that several different molecular defects cause the Kell null phenotype.

    Funded by: NHLBI NIH HHS: HL54459

    The Journal of biological chemistry 2001;276;29;27281-9

  • Molecular basis of the Kell-null phenotype: a mutation at the splice site of human KEL gene abolishes the expression of Kell blood group antigens.

    Yu LC, Twu YC, Chang CY and Lin M

    Transfusion Medicine Laboratory, Department of Medical Research, Mackay Memorial Hospital, Taipei 251, Taiwan.

    The Kell blood group system is polymorphic, and 23 antigens have been defined to date. The Kell antigens are located on a single red cell transmembrane glycoprotein, encoded by the 19 exons of the KEL gene. The different Kell phenotypes result from point mutations leading to amino acid changes in the Kell glycoprotein. An unusual phenotype, which is defined as the complete lack of all of the Kell antigens, has been identified and designated as the Kell-null or Ko phenotype. The coding region of the KEL gene of the Ko individual showed a normal KEL2/KEL4/KEL7 gene sequence; nevertheless, a G to C mutation at the splice donor site (5' splice site) of intron 3 was found to be present as a homozygote in the individual. The mutation destroys the conserved GT sequence of the splice donor site. Reverse transcription-polymerase chain reaction analysis showed the absence of the complete KEL mRNA. Instead, a major transcript with the exon 3 region skipped was found. The exon 3 of the KEL gene encodes the transmembrane domain of the Kell glycoprotein, and a transcript without exon 3 is predicted to have a premature stop codon that abolishes the translation of C-terminal segment. The segment contains all of the known positions responsible for characterizing different Kell antigens, and this explains the lack of all Kell antigens in Ko red cells.

    The Journal of biological chemistry 2001;276;13;10247-52

  • Disulfide bonds in big ET-1 are essential for the specific cleavage at the Trp(21)-Val(22) bond by soluble endothelin converting enzyme-1 from baculovirus/insect cells.

    Fahnoe DC, Johnson GD, Herman SB and Ahn K

    Parke-Davis Pharmaceutical Research, Ann Arbor, Michigan 48105, USA.

    Endothelin converting enzyme-1 (ECE-1) is a type II integral membrane protein and a zinc metalloendopeptidase. ECE-1 generates endothelin-1 (ET-1), the most potent vasoconstrictor yet discovered, by specific proteolytic processing of a precursor peptide, big ET-1. An insect cell expression system, which generates up to 4.3 mg of a secreted, soluble form of ECE-1 (solECE-1) per liter culture medium, has been established and solECE-1 was purified to homogeneity using five chromatographic steps. SolECE-1 expressed in insect cells could be suitable for X-ray structure determination as it is much less glycosylated than solECE-1 from mammalian cells. SolECE-1 from both sources, nonetheless, has comparable enzymatic properties. Despite apparent structural similarities, ECE-1 cleaves big ET-1 exclusively between Trp(21) and Val(22), in contrast to neprilysin, which cleaves big ET-1 at various sites. However, when linear big ET-1, in which the formation of disulfide bonds has been prevented by alkylation of the four cysteines, was used as substrate, it was cleaved by solECE-1 at multiple sites. This result indicates that secondary/tertiary structure of big ET-1 induced by disulfide bonds is essential for the specific cleavage of the Trp(21)-Val(22) bond by ECE-1. A continuous, fluorescent ECE-1 assay has been developed using a novel substrate, 2-aminobenzoyl-Arg-Pro-Pro-Gly-Phe-Ser-Pro-(p-nitro-Phe(8))-Arg. This simple and rapid assay can greatly facilitate discovery of novel ECE inhibitors useful as pharmaceutical agents.

    Archives of biochemistry and biophysics 2000;373;2;385-93

  • Intracellular assembly of Kell and XK blood group proteins.

    Russo D, Lee S and Redman C

    Lindsley F. Kimball Research Institute, The New York Blood Center, 310 East 67 Street, New York, NY, USA.

    Kell, a 93 kDa type II membrane glycoprotein, and XK, a 444 amino acid multi-pass membrane protein, are blood group proteins that exist as a disulfide-bonded complex on human red cells. The mechanism of Kell/XK assembly was studied in transfected COS cells co-expressing Kell and XK proteins. Time course studies combined with endonuclease-H treatment and cell fractionation showed that Kell and XK are assembled in the endoplasmic reticulum. At later times the Kell component of the complex was not cleaved by endonuclease-H, indicating N-linked oligosaccharide processing and transport of the complex to a Golgi and/or a post-Golgi cell fraction. Surface-labeling of transfected COS cells, expressing both Kell and XK, demonstrated that the Kell/XK complex travels to the plasma membrane. XK expressed in the absence of Kell was also transported to the cell surface indicating that linkage of Kell and XK is not obligatory for cell surface expression.

    Funded by: NHLBI NIH HHS: HL54459

    Biochimica et biophysica acta 1999;1461;1;10-8

  • Proteolytic processing of big endothelin-3 by the kell blood group protein.

    Lee S, Lin M, Mele A, Cao Y, Farmar J, Russo D and Redman C

    The Lindsley F. Kimball Research Institute of the New York Blood Center, New York, NY, USA. slee@nybc.org

    Kell blood group protein shares a consensus sequence (H.E.X.X.H) with a large family of zinc-dependent endopeptidases. Kell has closest homology with neutral endopeptidase 24.11, endothelin converting enzyme-1 (ECE-1), and the PEX gene product that, as a group, comprise the M13 subfamily of mammalian neutral endopeptidases. The proteolytic activity of the M13 members, but not of Kell, has been previously demonstrated. A secreted form of wild-type Kell protein (s-Kell), devoid of the intracellular and transmembrane domains, was expressed in sf9 cells. As a negative control, an inactive mutant Kell protein (E582G) was expressed. As determined by N-terminal amino acid sequencing and mass spectrometry of the cleaved products, wild-type s-Kell, but not the control mutant protein, specifically cleaved big endothelin-3 (ET-3) at Trp(21)-Ile(22), yielding ET-3, and, to a much lesser extent, also cleaved big ET-1 and big ET-2 at Trp(21)-Val(22), yielding ET-1 and ET-2. Enzymatic activity was partially inhibited by phosphoramidon. s-Kell has an acidic pH optimum (pH 6.0 to 6.5). Like the recombinant protein, red blood cells of common Kell phenotype also preferentially process big ET-3, in contrast to Ko (null) cells that do not. These data demonstrate that the Kell blood group protein is a proteolytic enzyme that processes big ET-3, generating ET-3, a potent bioactive peptide with multiple biological roles.

    Funded by: NHLBI NIH HHS: HL54459

    Blood 1999;94;4;1440-50

  • Kell and Kx, two disulfide-linked proteins of the human erythrocyte membrane are phosphorylated in vivo.

    Carbonnet F, Hattab C, Cartron JP and Bertrand O

    INSERM U76, Institut National de la Transfusion Sanguine, Paris, France.

    Kell and Kx are two quantitatively minor proteins from the human erythrocyte membrane which carry blood groups antigens and are thought to be a metalloprotease and a membrane transporter, respectively. In the red cell membrane, these proteins form a complex stabilized by disulfide bond(s). Phosphorylation status of these proteins was studied, in the presence or absence of effectors of several kinases, either on intact cells incubated with [32P]-orthophosphate or on ghosts incubated with [gamma-32P]ATP. Purification of Kell-Kx complex, by immunochromatography on an immobilized human monoclonal antibody of Kell blood group specificity allowed to establish that (i) neither protein is phosphorylated on tyrosine; (ii) the Kell protein is a putative substrate for Casein Kinase II (CKII) and Casein Kinase I (CKI) but not for protein kinase C (PKC), whereas Kx protein is phosphorylated by CKII and PKC but not by CKI; (iii) Protein Kinase A neither phosphorylates the Kell nor the Kx proteins.

    Biochemical and biophysical research communications 1998;247;3;569-75

  • Kell typing by allele-specific PCR (ASP).

    Avent ND and Martin PG

    International Blood Group Reference Laboratory, Southmead, Bristol.

    The Kell blood group system is important in transfusion medicine, and the Kell antigen (K1) is probably second in importance to Rh D as an immunogen in alloimmunized pregnancies which cause haemolytic disease of the newborn. The K/k (K1/K2) blood group polymorphism has been recently defined. A point mutation changes Thr193 (k) to Met193 (K) in the Kell glycoprotein. The mutation which creates K destroys a consensus N-glycan addition site. We describe a simple PCR test for K blood group typing. The test is based on the use of an allele-specific K-primer. We have shown the test to give results in complete concordance with serologically defined Kell blood group status using 65 genomic DNA samples derived from both amniocytes and peripheral blood lymphocytes. The test is suitable for the prenatal determination of Kell type.

    British journal of haematology 1996;93;3;728-30

  • Point mutations characterize KEL10, the KEL3, KEL4, and KEL21 alleles, and the KEL17 and KEL11 alleles.

    Lee S, Wu X, Son S, Naime D, Reid M, Okubo Y, Sistonen P and Redman C

    Lindsley F. Kimball Research Institute, New York Blood Center, New York, USA.

    Background: The Kell blood group system is complex, consisting of five sets of alleles and expressing high- and low-incidence antigens and at least 11 other independently expressed antigens. The molecular basis of two sets of alleles: KEL1 (K) and KEL2 (k) and KEL6 (Jsa) and KEL7 (Jsb) have been elucidated as single-base mutations leading to amino acid changes. The molecular basis for the KEL3 (Kpa), KEL4 (Kpb), and KEL21 (Kpc) alleles, the KEL11(Cote) and KEL17(Wka) alleles, and for KEL10 (UIa) is now reported.

    Genomic DNA from unrelated individuals with KEL:3,-4,-21 [Kp(a+b-c-)], KEL:-3,-4,21 [Kp(a-b-c+)], KEL:17,-11, and KEL:10 (UIa) phenotypes was amplified by polymerase chain reaction (PCR) with primers for the 19 exons of KEL. The PCR products were sequenced and compared to the DNA sequences of a common Kell system phenotype, KEL:-3,4,-21,-17,-10. Base mutations found were confirmed by restriction fragment length polymorphism analysis in which DNA of unrelated persons with similar red cell phenotypes was used.

    Results: In all cases, single-base mutations were responsible for the expression of the various antigens. In KEL3 (Kpa), KEL4 (Kpb), and KEL21 (Kpc), point mutations at the same codon in exon 8, encoding amino acid residue 281, distinguish the three genes. KEL4 has the CGG codon for arginine, KEL3 has the TGG codon for tryptophan, and KEL21 has the CAG codon for glutamine. KEL17 has a T1025C mutation in exon 8, encoding a valine-to-alanine amino acid change at residue 302. KEL10 has an A1601T mutation in exon 13, encoding a glutamic acid-to-valine change at residue 494. In all cases, the point mutations created restriction enzyme sites, and PCR-based restriction fragment length polymorphisms confirmed that these point mutations occurred in unrelated persons with the same red cell phenotype.

    Conclusion: Single-base substitutions characterize the KEL3, KEL21, KEL17, and KEL10 genes. The allelic relationship of KEL3, KEL4, and KEL21 was confirmed because the mutations occur in the same codon, expressing different amino acids. PCR-based restriction fragment length polymorphisms can be used to distinguish genotypes.

    Funded by: NHLBI NIH HHS: HL 3384, HL54459

    Transfusion 1996;36;6;490-4

  • Molecular basis of the K:6,-7 [Js(a+b-)] phenotype in the Kell blood group system.

    Lee S, Wu X, Reid M and Redman C

    Lindsley F. Kimball Research Institute of the New York Blood Center, New York, USA.

    Background: The Kell blood group system consists of at least 21 antigens. KEL6(Jsa) is a low-incidence antigen that has an antithetical relationship with the high-incidence KEL7(Jsb) antigen. The molecular basis of KEL6 that appears in less than 1.0 percent of the general population, but in up to 19.5 percent of African Americans, was unknown.

    Nineteen exons of the Kell gene (KEL) were amplified by polymerase chain reaction (PCR) assays of genomic DNA obtained from individuals with K:6,-7 [Js(a+b-)] phenotype. The PCR products were sequenced. A comparison was made of the sequence of the PCR products and the sequence of K:-6,7, the common phenotype.

    Results: KEL from individuals with the K:6,-7 phenotype had two base substitutions in exon 17. One was a missense mutation (T-to-C base substitution) at nucleotide (nt) 1910, which predicts an amino acid change from leucine to proline; the other was a silent substitution (A-to-C) at nt 2019. The T-to-C substitution eliminated a restriction site for Mnl I, whereas the A-to-G substitution eliminated a Dde I site. Analyses of exon 17 in seven unrelated persons with K:6,-7 phenotype by Mnl I and Dde I enzymes showed the expected presence of restriction fragment length polymorphisms.

    Conclusion: The base substitutions T-to-C at nt 1910 and A-to-G at nt 2019 are unique to KEL6. The predicted Leu-->Pro change may disrupt the alpha-helical structure and thus form the epitope for KEL6.

    Funded by: NHLBI NIH HHS: HL 3384

    Transfusion 1995;35;10;822-5

  • Purification and partial characterization of the erythrocyte Kx protein deficient in McLeod patients.

    Khamlichi S, Bailly P, Blanchard D, Goossens D, Cartron JP and Bertrand O

    INSERM U76, Institut National de la Transfusion Sanguine, Paris, France.

    A 37-kDa protein was immunopurified from human erythrocytes as a complex with a monoclonal antibody directed against the Kell blood group protein of 93 kDa. A rabbit antibody raised against the purified complex reacted on a Western blot with the 93-kDa and 37-kDa proteins and was able to immunoprecipitate the 37-kDa component from K0 erythrocytes which express large amount of the Kx antigen, but not from erythrocytes of patients suffering from McLeod syndrome, a X-linked disorder in which the Kx antigen is lacking. Additional studies have shown that the 37-kDa protein is not glycosylated, and permitted the sequence of the 22 first N-terminal amino acids to be established. This sequence was identical to the predicted protein product of the XK gene cloned recently, which is deleted or mutated in McLeod patients [Ho, M., Chelly, J., Carter, N., Danek, A., Crocker, P. & Monaco, A. P. (1994) Cell 77, 869-880]. Our findings provide strong evidence that the 37-kDa red cell membrane protein is identical to the Kx protein produced by the XK structural gene and demonstrate that Kx and Kell proteins are two subunits expressed as a complex hold by disulfide bond(s) at the red cell surface.

    European journal of biochemistry 1995;228;3;931-4

  • Organization of the gene encoding the human Kell blood group protein.

    Lee S, Zambas E, Green ED and Redman C

    Lindsley F. Kimball Research Institute, New York Blood Center, New York.

    Kell is one of the major blood group systems in human erythrocytes. It is a complex system containing a large number of different antigens. Previously we cloned the Kell cDNA, which was predicted to encode an integral membrane protein with 731 amino acids. Now we have isolated overlapping genomic clones and determined the exon-intron structure of the KEL gene; it spans approximately 21.5 kb with its coding sequence being organized in 19 exons that range in size from 63 bp to 288 bp. The size of introns ranges from 93 bp to approximately 6 kb. The donor and acceptor splice sites all conform to the consensus splicing sequences. Exon 1 encodes only the initiation amino acid, methionine, and contains a consensus Sp1 binding site. The single membrane spanning region of Kell protein is encoded in exon 3 and the putative zinc endopeptidase active site is in exon 16. The amino acids encoded by the 19 exons are identical to those of a person with a common Kell phenotype, as determined by RNA polymerase chain reaction of peripheral blood. Amplification of cDNA 5' ends, derived from human fetal liver, indicated three transcription initiation sites located 30, 81, and 120 bp upstream of the initiation codon. The 5' flanking region of KEL from -176 does not contain a TATA sequence, but has possible GATA-1 binding sites and has significant promoter activity when determined by chloramphenicol acetyltransferase activity in K562 cells.

    Funded by: NHLBI NIH HHS: HL35841

    Blood 1995;85;5;1364-70

  • Molecular basis of the Kell (K1) phenotype.

    Lee S, Wu X, Reid M, Zelinski T and Redman C

    Lindsley F. Kimball Research Institute of the New York Blood Center.

    K1 (K, Kell) is a strong immunogen; its antibodies can cause severe reactions if incompatible blood is transfused and may cause hemolytic disease of the newborn in sensitized mothers. K1 is a member of the Kell blood group system, which is complex, containing over 20 different antigens. Some of the antigens are organized in allelic pairs of high and low prevalence whereas others are independently expressed. K1, which is present in 9% of the population, is antithetical to the high-prevalence K2 (k) antigen. We have determined the molecular basis of the K1/K2 polymorphism by sequencing the 19 exons of the Kell gene (KEL) of a K1/K1 person. Polymerase chain reaction was performed on genomic DNA isolated from peripheral blood and the amplified products were either directly sequenced or subcloned and sequenced. Comparisons of K1/K1 and K2/K2 DNA showed a C to T base substitution in exon 6 that predicts a threonine to methionine change at amino acid residue 193. This amino acid substitution occurs at a consensus N-glycosylation site (Asn. X. Thr) and probably prevents N-glycosylation, leading to a change in phenotype. The C to T substitution creates a Bsm I restriction enzyme site, which was tested in 42 different samples to confirm that this base change identifies the K1/K1 genotype. This test differentiates genotypes, K1/K1, K2/K2, and the K1/K2 heterozygote and should prove useful in the prenatal diagnosis of K1-related hemolytic disease of the newborn.

    Funded by: NHLBI NIH HHS: HL35841

    Blood 1995;85;4;912-6

  • The human Kell blood group gene maps to chromosome 7q33 and its expression is restricted to erythroid cells.

    Lee S, Zambas ED, Marsh WL and Redman CM

    Lindsley F. Kimball Research Institute, New York Blood Center, NY 10021.

    The Kell blood group is one of the major antigenic systems in human red blood cells. To determine the location of the Kell gene on human chromosomes, panels containing genomic DNA of human-hamster somatic cell hybrids were hybridized with radiolabeled cDNA probe specific for the Kell locus. Only the samples containing DNA from chromosome 7 gave positive hybridization signals. In situ hybridization analysis, using genomic clones isolated with the cDNA, localized the KEL gene to 7q33. Northern blot analysis of poly(A)+ RNA from human brain, kidney, lung, fetal and adult liver, and bone marrow showed that Kell transcripts were only present in fetal liver and bone marrow. This indicates that the Kell protein, which carries the Kell antigens, may only be expressed in erythroid tissues.

    Funded by: NHLBI NIH HHS: HL33841

    Blood 1993;81;10;2804-9

  • Molecular cloning and primary structure of Kell blood group protein.

    Lee S, Zambas ED, Marsh WL and Redman CM

    Lindsley F. Kimball Research Institute of the New York Blood Center, NY 10021.

    The Kell blood group is a major antigenic system in human erythrocytes. Kell antigens reside on a 93-kDa membrane glycoprotein that is surface-exposed and associated with the underlying cytoskeleton. We isolated tryptic peptides and, based on the amino acid sequence of one of the peptides and by using the PCR, prepared a specific oligonucleotide to screen a lambda gt10 human bone-marrow cDNA library. Four clones were isolated, one containing cDNA with an open reading frame for an 83-kDa protein. All known Kell amino acid sequences were present in the deduced sequence; moreover, rabbit antibody to a 30-amino acid peptide, prepared from this sequence, reacted on an immunoblot with authentic Kell protein. The Kell cDNA sequence predicts a 732-amino acid protein. Hydropathy analysis indicates a single membrane-spanning region, suggesting that Kell protein is oriented with 47 of its N-terminal amino acids in the cell cytoplasm, and a 665-amino acid segment, which contains six possible N-glycosylation sites, is located extracellularly. Computer-based search showed that Kell has structural and sequence homology to a family of zinc metalloglycoproteins with neutral endopeptidase activity.

    Funded by: NHLBI NIH HHS: HL-33841

    Proceedings of the National Academy of Sciences of the United States of America 1991;88;14;6353-7

  • Recent developments in the Kell blood group system.

    Marsh WL and Redman CM

    Lindsley F. Kimball Research Institute, New York Blood Center, NY 10021.

    Funded by: NHLBI NIH HHS: HL33841

    Transfusion medicine reviews 1987;1;1;4-20

  • A new Kell blood-group phenotype.


    Nature 1957;180;4588;711

Gene lists (2)

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
L00000016 G2C Homo sapiens Human PSP Human orthologues of mouse PSP adapted from Collins et al (2006) 1121
© 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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