Signal Regulatory Protein Beta 2 (SIRPb2)

Signal-regulatory protein beta-2 is a member of the signal-regulatory-protein (SIRP) family, and also belongs to the immunoglobulin superfamily. SIRP family members are receptor-type transmembrane glycoproteins known to be involved in the negative regulation of receptor tyrosine kinase-coupled signaling processes. This protein was found to interact with TYROBP/DAP12, a protein bearing immunoreceptor tyrosine-based activation motifs.

Until now, the expression, specificity and function of the recently identified member of the signal-regulatory protein (SIRP) family, SIRP-β2, was unknown. Reporting in Blood, Marco Colonna and colleagues now show that SIRP-β2 has an important role in T-cell adhesion to antigen-presenting cells (APCs), through binding CD47, and that this co-stimulates T-cell proliferation.