CD72 (E4K4A) Rabbit mAb #28182

CD72 is an inhibitory co-receptor of the B cell antigen receptor (BCR) and is expressed primarily on B cells (1,2). The cytoplasmic domain of CD72 contains immunoreceptor tyrosine-based inhibition motifs (ITIMs) that are phosphorylated by Lyn when Lyn associates with BCR (3-5). This phosphorylation leads to recruitment of SHP-1 to CD72 and negative regulation of BCR signaling (4,5). The extracellular portion of CD72 contains a C-type lectin domain, and binding its ligand, CD100/Semaphorin-4D, leads to dissociation of CD72 and SHP-1 and thus relief of BCR signaling suppression (6,7). Recently, Semaphorin-3A was also reported to act as a ligand for CD72; however, unlike CD100/Semaphorin-4D, association with Semaphorin-3A induces CD72 ITAM phosphorylation and association of CD72 with SHP-1 (8). CD72 also plays a role in systemic lupus erythematosus (SLE); through its recognition of the self-antigen Sm/RNP, CD72 suppresses the TLR7-dependent B cell response to nucleic acid self-antigens, inhibiting SLE development (9).