SIRPG 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. Alternatively spliced transcript variants encoding different isoforms have been described. Recombinant human SIRPG protein, fused to His-tag at N-terminus, was expressed in E.coli.