LYN, FYN, BLK phosphorylate ITAMs of Ig-alpha (CD79A) and Ig-beta (CD79B)

Stable Identifier
Reaction [transition]
Homo sapiens
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The B cell receptor (BCR) comprises an immunoglobulin complexed with a heterodimer of Ig-alpha (CD79A, MB-1) and Ig-beta (CD79B, B29). After immunoglobulin IgM or IgD binds antigen the associated Ig-alpha and Ig-beta are each observed to be phosphorylated at two tyrosine residues in the cytoplasmic immunoreceptor tyrosine-activated motif (ITAM) (Sanchez et al. 1993, Hata et al. 1994, Saouaf et al. 1994, Saouaf et al. 1995). Saouaf et al. (1995) showed that the kinase Blk could phosphorylate both tyrosines of each ITAM and that the kinase SYK specifically bound phosphorylated but not unphosphorylated ITAMs. In mouse the kinase Lyn and other kinases phosphorylate one tyrosine and Syk is believed to phosphorylate the other (Yamanashi et al. 1991, Flaswinkel and Reth 1994, Rolli et al. 2002). SHP1 regulates BCR signaling by dephosphorylating CD79A/CD79B (IGA/IGB) and its downstream signaling molecules SYK and SLP65 promoting Ca2+ efflux from the cell9 (Adachi et al. 2001, Chen et al. 2004).
Literature References
PubMed ID Title Journal Year
7592958 Reconstitution of the B cell antigen receptor signaling components in COS cells

Saouaf, SJ, Mahajan, S, Bolen, JB, Fargnoli, J, Kut, SA, Rowley, RB

J Biol Chem 1995
1702903 Association of B cell antigen receptor with protein tyrosine kinase Lyn

Yamamoto, T, Yamanashi, Y, Mizuguchi, J, Toyoshima, K, Kakiuchi, T

Science 1991
7927516 Tyrosine phosphorylation of MB-1, B29, and HS1 proteins in human B cells following receptor crosslinking

Kawakami, T, Nakamura, T, Hata, D, Mayumi, M, Herren, B, Kawakami, Y

Immunol Lett 1994
7688784 Signal transduction by immunoglobulin is mediated through Ig alpha and Ig beta

Bolen, JB, Mahajan, S, Franke, R, Costa, T, Burkhardt, AL, Sanchez, M, Nussenzweig, M, Misulovin, Z

J Exp Med 1993
8306975 Dual role of the tyrosine activation motif of the Ig-alpha protein during signal transduction via the B cell antigen receptor

Reth, M, Flaswinkel, H

EMBO J 1994
7524079 Temporal differences in the activation of three classes of non-transmembrane protein tyrosine kinases following B-cell antigen receptor surface engagement

Saouaf, SJ, Bolen, JB, Tsukada, S, Fargnoli, J, Mahajan, S, Burkhardt, AL, Kut, SA, Rowley, RB, Witte, ON

Proc Natl Acad Sci U S A 1994
12453414 Amplification of B cell antigen receptor signaling by a Syk/ITAM positive feedback loop

Flemming, A, Reth, M, Zürn, C, Rolli, V, Gallwitz, M, Wossning, T, Schamel, WW

Mol Cell 2002
Catalyst Activity

protein tyrosine kinase activity of LYN,FYN,BLK [plasma membrane]

This event is regulated
Inferred From
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