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MGP000472

UniProt Annotations

Entry Information

Gene Name	CD79a molecule, immunoglobulin-associated alpha
Protein Entry	CD79A_HUMAN
UniProt ID	P11912
Species	Human

Comments

Comment type	Description
Alternative Products	Event=Alternative splicing; Named isoforms=2; Name=1; Synonyms=Long; IsoId=P11912-1; Sequence=Displayed; Name=2; Synonyms=Short; IsoId=P11912-2; Sequence=VSP_002476;
Disease	Agammaglobulinemia 3, autosomal recessive (AGM3) [MIM:613501]: A primary immunodeficiency characterized by profoundly low or absent serum antibodies and low or absent circulating B-cells due to an early block of B-cell development. Affected individuals develop severe infections in the first years of life. {ECO:0000269\|PubMed:10525050, ECO:0000269\|PubMed:11920841}. Note=The disease is caused by mutations affecting the gene represented in this entry. Two different mutations, one at the splice donor site of intron 2 and the other at the splice acceptor site for exon 3, have been identified. Both mutations give rise to a truncated protein.
Function	Required in cooperation with CD79B for initiation of the signal transduction cascade activated by binding of antigen to the B-cell antigen receptor complex (BCR) which leads to internalization of the complex, trafficking to late endosomes and antigen presentation. Also required for BCR surface expression and for efficient differentiation of pro- and pre-B-cells. Stimulates SYK autophosphorylation and activation. Binds to BLNK, bringing BLNK into proximity with SYK and allowing SYK to phosphorylate BLNK. Also interacts with and increases activity of some Src- family tyrosine kinases. Represses BCR signaling during development of immature B-cells. {ECO:0000269\|PubMed:8617796, ECO:0000269\|PubMed:9057631}.
Ptm	Arginine methylation in the ITAM domain may interfere with the binding of SYK. It promotes signals leading to B-cell differentiation (By similarity). {ECO:0000250}.
Ptm	Phosphorylated on tyrosine, serine and threonine residues upon B-cell activation. Phosphorylation of tyrosine residues by Src-family kinases is an early and essential feature of the BCR signaling cascade. The phosphorylated tyrosines serve as docking sites for SH2-domain containing kinases, leading to their activation which in turn leads to phosphorylation of downstream targets. Phosphorylated by LYN. Phosphorylation of serine and threonine residues may prevent subsequent tyrosine phosphorylation. {ECO:0000269\|PubMed:10748115, ECO:0000269\|PubMed:10900006}.
Similarity	Contains 1 Ig-like C2-type (immunoglobulin-like) domain. {ECO:0000305}.
Similarity	Contains 1 ITAM domain. {ECO:0000255\|PROSITE- ProRule:PRU00379}.
Subcellular Location	Cell membrane; Single-pass type I membrane protein. Note=Following antigen binding, the BCR has been shown to translocate from detergent-soluble regions of the cell membrane to lipid rafts although signal transduction through the complex can also occur outside lipid rafts. {ECO:0000250}.
Subunit	Heterodimer of alpha and beta chains; disulfide-linked. Part of the B-cell antigen receptor complex where the alpha/beta chain heterodimer is non-covalently associated with an antigen- specific membrane-bound surface immunoglobulin of two heavy chains and two light chains. Interacts through its phosphorylated ITAM domain with the SH2 domains of SYK which stimulates SYK autophosphorylation and activation. Also interacts, when phosphorylated on Tyr-210, with the SH2 domain of BLNK/SLP65, bringing BLNK into proximity with SYK and allowing SYK to phosphorylate BLNK which is necessary for trafficking of the BCR to late endosomes. Interacts with Src-family tyrosine kinases including FYN and LYN, increasing their activity (By similarity). {ECO:0000250}.
Tissue Specificity	B-cells.
Web Resource	Name=CD79Abase; Note=CD79A mutation db; URL="http://structure.bmc.lu.se/idbase/CD79Abase/";