Signal regulatory protein beta-1 (SIRPB1) (SIRPB1)

Signal regulatory protein beta-1 (SIRPB1) is a transmembrane glycoprotein receptor in the signal regulatory protein (SIRP) family within the immunoglobulin superfamily. It is primarily expressed on myeloid cells such as macrophages, dendritic cells, granulocytes, and microglia. Unlike the inhibitory SIRP alpha (SIRPA), SIRPB1 functions as an activating receptor due to its association with the adaptor protein DAP12 (TYROBP) via a charged lysine in its transmembrane domain, lacking inhibitory ITIM motifs in its short cytoplasmic tail. This enables ITAM-mediated signaling that promotes phosphorylation of downstream kinases like Syk and ZAP-70, enhancing immune responses including phagocytosis of pathogens or debris (e.g., amyloid-β aggregates), pro-inflammatory cytokine release (TNF-α, IL-6, IL-1β), cell adhesion, migration, and potential tumor cell recognition. SIRPB1 has three Ig-like extracellular domains and is involved in innate immunity regulation, with implications in immunotherapy for boosting anti-tumor phagocytosis and managing inflammatory disorders.

Other names

SIRP beta-1SIRP-β1SIRPβ1CD172bSIRBL