UniProtSummary | FUNCTION:SwissProt:P11912#RequiredincooperationwithCD79BforinitiationofthesignaltransductioncascadeactivatedbybindingofantigentotheB-cellantigenreceptorcomplex(BCR)whichleadstointernalizationofthecomplex,traffickingtolateendosomesandantigenpresentation.AlsorequiredforBCRsurfaceexpressionandforefficientdifferentiationofpro-andpre-B-cells.StimulatesSYKautophosphorylationandactivation.BindstoBLNK,bringingBLNKintoproximitywithSYKandallowingSYKtophosphorylateBLNK.AlsointeractswithandincreasesactivityofsomeSrc-familytyrosinekinases.RepressesBCRsignalingduringdevelopmentofimmatureBcells. SIZE:226aminoacids;25038Da SUBUNIT:Heterodimerofalphaandbetachains;disulfide-linked.PartoftheB-cellantigenreceptorcomplexwherethealpha/betachainheterodimerisnon-covalentlyassociatedwithanantigen-specificmembrane-boundsurfaceimmunoglobulinoftwoheavychainsandtwolightchains.InteractsthroughitsphosphorylatedITAMdomainwiththeSH2domainsofSYKwhichstimulatesSYKautophosphorylationandactivation.Alsointeracts,whenphosphorylatedonTyr-210,withtheSH2domainofBLNK/SLP65,bringingBLNKintoproximitywithSYKandallowingSYKtophosphorylateBLNKwhichisnecessaryfortraffickingoftheBCRtolateendosomes.InteractswithSrc-familytyrosinekinasesincludingFYNandLYN,increasingtheiractivity(Bysimilarity). SUBCELLULARLOCATION:Cellmembrane;Single-passtypeImembraneprotein.Note=Followingantigenbinding,theBCRhasbeenshowntotranslocatefromdetergent-solubleregionsofthecellmembranetolipidraftsalthoughsignaltransductionthroughthecomplexcanalsooccuroutsidelipidrafts(Bysimilarity). TISSUESPECIFICITY:B-cells. PTM:Phosphorylatedontyrosine,serineandthreonineresiduesuponB-cellactivation.PhosphorylationoftyrosineresiduesbySrc-familykinasesisanearlyandessentialfeatureoftheBCRsignalingcascade.ThephosphorylatedtyrosinesserveasdockingsitesforSH2-domaincontainingkinases,leADIngtotheiractivationwhichinturnleadstophosphorylationofdownstreamtargets.Phosphorylationofserineandthreonineresiduesmaypreventsubsequenttyrosinephosphorylation. DISEASE:SwissProt:P11912#DefectsinCD79Aareacauseofnon-Brutontypeagammaglobulinemia[MIM:601495].AgammaglobulinemiaisanimmunodeficiencydiseasewhichresultsindevelopmentaldefectsinthematurationpathwayofB-cells.Twodifferentmutations,oneatthesplicedonorsiteofintron2andtheotheratthespliceacceptorsiteforexon3,havebeenidentified.Bothmutationsgiverisetoatruncatedprotein. SIMILARITY:SwissProt:P11912##Contains1Ig-likeC2-type(immunoglobulin-like)domain.&Contains1ITAMdomain. |