Signal regulatory proteins (SIRPs) are a class of transmembrane glycoproteins with extracellular domains resembling the immunoglobulins. The SIRP family consists of three members, SIRPα, SIRPβ and SIRPγ. In rat there are two SIRPβ members, SIRPβ1 and SIRPβ2. SIRP members are ubiquitously present on the surface of all immune system cells. SIRPα (SHP-1) is expressed on neurons, myeloid dendritic cells, mast cells, macrophages and granulocytes. The most studied role of SIRPα is the inhibition of host cell phagocytosis by the macrophages. SIRPα is reportedly involved in clearance of aged erythrocytes, regulation of production of TNF-α induced by LPS, controlling the migration of myeloid cells and maturation of dendritic cells
Anti-SIRPα1 (SHPS-1) recognizes the differentially glycosylated forms of SIRPα1(SHPS-1) of 130, 100 and 65 kDa. It also detects a single band at 50 kDa.
