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CD79A; B-cell antigen receptor complex-associated protein alpha chain; Ig-alpha; MB-1 membrane glycoprotein; surface IgM-associated protein; membrane-bound immunoglobulin-associated protein (CD79A, IGA, MB1)
Function:
- component of B-cell antigen receptor
- 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 & antigen presentation
- also required for BCR surface expression & for efficient differentiation of pro- & pre-B-cells
- stimulates SYK autophosphorylation & activation
- binds to BLNK, bringing BLNK into proximity with SYK & allowing SYK to phosphorylate BLNK
- also interacts with & increases activity of some Src-family tyrosine kinases
- represses BCR signaling during development of immature B cells phosphorylated on Tyr, Ser & Thr upon B-cell activation
- phosphorylation of Tyr by Src-family kinases is an early & essential feature of the BCR signaling cascade the phosphorylated Tyr serve as docking sites for SH2-domain containing kinases, leading to their activation which in turn leads to phosphorylation of downstream targets
- phosphorylation of Ser & Thr may prevent subsequent Tyr phosphorylation
- 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 & two light chains
- interacts through its phosphorylated ITAM domain with the SH2 domains of SYK which stimulates SYK autophosphorylation & activation
- also interacts, when phosphorylated on Tyr-210, with the SH2 domain of BLNK/SLP65, bringing BLNK into proximity with SYK & allowing SYK to phosphorylate BLNK which is necessary for trafficking of the BCR to late endosomes
- interacts with Src-family tyrosine kinases including FYN & LYN, increasing their activity (putative)
Structure:
- heterodimer of alpha & beta chains, disulfide-linked
- contains 1 Ig-like C2-type domain (immunoglobulin-like)
- contains 1 ITAM domain
Compartment:
- cell membrane; single-pass type I membrane protein
- following antigen binding, B-cell receptor translocates from detergent-soluble regions of the cell membrane to lipid rafts although signal transduction through the complex can also occur outside lipid rafts (putative)
Alternative splicing: at least 2 isoforms
Expression:
- B-cells
- early B cell differentiation
- plasma cells
- acute lymphoblastic leukemia
- B cell lymphoma
- lymphocyte-predominant Hodgkin's lymphoma
Pathology:
- defects in CD79A are a cause of non-Bruton type agammaglobulinemia
- somatic hypermutation of gene seen in
a) B cell lymphoma
b) multiple myeloma
General
glycoprotein
plasma membrane protein
protein subunit
Properties
SIZE: entity length = 226 aa
MW = 25 kD
COMPARTMENT: cellular membrane
MOTIF: signal sequence {1-32}
immunoglobulin superfamily domain {33-116}
MOTIF: cysteine residue {C54}
MODIFICATION: cysteine residue {C106}
N-glycosylation site {N57}
N-glycosylation site {N63}
N-glycosylation site {N73}
N-glycosylation site {N88}
N-glycosylation site {N97}
cysteine residue {C106}
MODIFICATION: cysteine residue {C54}
N-glycosylation site {N112}
cysteine residue {C119}
MODIFICATION: cysteine residue {C136 IN BETA CHAIN}
transmembrane domain {144-165}
ITAM {177-205}
MOTIF: Tyr phosphorylation site {Y188}
tyrosine residue {210}
Tyr phosphorylation site {Y210}
Database Correlations
OMIM correlations
UniProt P11912
PFAM correlations
Entrez Gene 973
Kegg hsa:973
References
- UniProt :accession P11912
- Entrez Gene :accession 973
- http://www.pathologyoutlines.com/cdmarkers.html
20 May 2003
- CD79Abase; Note: CD79A mutation db
http://bioinf.uta.fi/CD79Abase/
Component-of
CD79 or B-cell antigen receptor complex-associated protein