P40293 (CD79A_BOVIN) Reviewed, UniProtKB/Swiss-Prot
Last modified February 19, 2014. Version 109. History...
Names and origin
|Protein names||Recommended name:|
B-cell antigen receptor complex-associated protein alpha chain
MB-1 membrane glycoprotein
Membrane-bound immunoglobulin-associated protein
Surface IgM-associated protein
|Organism||Bos taurus (Bovine) [Reference proteome]|
|Taxonomic identifier||9913 [NCBI]|
|Taxonomic lineage||Eukaryota › Metazoa › Chordata › Craniata › Vertebrata › Euteleostomi › Mammalia › Eutheria › Laurasiatheria › Cetartiodactyla › Ruminantia › Pecora › Bovidae › Bovinae › Bos|
|Sequence length||223 AA.|
|Sequence processing||The displayed sequence is further processed into a mature form.|
|Protein existence||Evidence at transcript level|
General annotation (Comments)
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 By similarity.
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-207, 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.
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 By similarity.
Phosphorylated on tyrosine, serine and threonine residues upon B-cell activation. Phosphorylation of tyrosine residues by Src-family kinases, including LYN, 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. Phosphorylation of serine and threonine residues may prevent subsequent tyrosine phosphorylation By similarity.
Arginine methylation in the ITAM domain may interfere with the binding of SYK. It promotes signals leading to B cell differentiation By similarity.
Contains 1 Ig-like C2-type (immunoglobulin-like) domain.
Contains 1 ITAM domain.
|This entry describes 2 isoforms produced by alternative splicing. [Align] [Select]|
|Isoform 1 (identifier: P40293-1) |
This isoform has been chosen as the 'canonical' sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.
|Isoform 2 (identifier: P40293-2) |
The sequence of this isoform differs from the canonical sequence as follows:
124-133: DPLPRPFLDM → ETMAEHEIRG
Sequence annotation (Features)
|Feature key||Position(s)||Length||Description||Graphical view||Feature identifier|
|Signal peptide||1 – 31||31||Potential|
|Chain||32 – 223||192||B-cell antigen receptor complex-associated protein alpha chain||PRO_0000014557|
|Topological domain||32 – 140||109||Extracellular Potential|
|Transmembrane||141 – 161||21||Helical; Potential|
|Topological domain||162 – 223||62||Cytoplasmic Potential|
|Domain||32 – 120||89||Ig-like C2-type|
|Domain||174 – 202||29||ITAM|
|Site||207||1||Required for binding to BLNK By similarity|
Amino acid modifications
|Modified residue||185||1||Phosphotyrosine; by SRC-type Tyr-kinases By similarity|
|Modified residue||196||1||Phosphotyrosine By similarity|
|Modified residue||201||1||Asymmetric dimethylarginine; by PRMT1 By similarity|
|Modified residue||207||1||Phosphotyrosine; by Tyr-kinases By similarity|
|Glycosylation||56||1||N-linked (GlcNAc...) Potential|
|Glycosylation||61||1||N-linked (GlcNAc...) Potential|
|Glycosylation||71||1||N-linked (GlcNAc...) Potential|
|Glycosylation||95||1||N-linked (GlcNAc...) Potential|
|Disulfide bond||53 ↔ 104||Potential|
|Disulfide bond||116||Interchain (with beta chain) Potential|
|Alternative sequence||124 – 133||10||DPLPRPFLDM → ETMAEHEIRG in isoform 2.||VSP_027221|
|Alternative sequence||134 – 223||90||Missing in isoform 2.||VSP_027222|
|||"Two forms of the mb-1 gene transcript in cattle."|
Youn H.-Y., Goitsuka R., Okuda M., Watari T., Tsujimoto H., Hasegawa A.
J. Immunol. 153:5127-5132(1994) [PubMed] [Europe PMC] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORMS 1 AND 2).
Tissue: Leukocyte and Lymphoblast.
|||"Molecular cloning of bovine mb-1 cDNA."|
Youn H.-Y., Goitsuka R., Kato H., Mason D.Y., Watari T., Tsujimoto H., Hasegawa A.
Vet. Immunol. Immunopathol. 52:191-200(1996) [PubMed] [Europe PMC] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1).
|||NIH - Mammalian Gene Collection (MGC) project|
Submitted (AUG-2006) to the EMBL/GenBank/DDBJ databases
Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 1).
|D16412 mRNA. Translation: BAA03899.1.|
D16459 mRNA. Translation: BAA03926.1.
BC120260 mRNA. Translation: AAI20261.1.
|RefSeq||NP_776691.2. NM_174266.4. |
3D structure databases
Protocols and materials databases
Genome annotation databases
|Ensembl||ENSBTAT00000002451; ENSBTAP00000002451; ENSBTAG00000001882. |
ENSBTAT00000031989; ENSBTAP00000031933; ENSBTAG00000001882.
Family and domain databases
|Gene3D||220.127.116.11. 1 hit. |
|InterPro||IPR007110. Ig-like_dom. |
|Pfam||PF07679. I-set. 1 hit. |
PF02189. ITAM. 1 hit.
|SMART||SM00408. IGc2. 1 hit. |
SM00077. ITAM. 1 hit.
|PROSITE||PS50835. IG_LIKE. 1 hit. |
PS51055. ITAM_1. 1 hit.
|Accession||Primary (citable) accession number: P40293|
Secondary accession number(s): Q0P5B8, Q28134
|Entry status||Reviewed (UniProtKB/Swiss-Prot)|
|Annotation program||Chordata Protein Annotation Program|
Index of protein domains and families