Biolegend, 568804, Biotinylated Recombinant Human SIRPα V2 (carrier-free)

Signal Regulatory Proteins (SIRPs) are a family of transmembrane glycoproteins with extracellular IgG domains. The extracellular regions of the SIRPs are comprised of three Ig-like loops; the proximal loop containing two IgC domains while the distal membrane loop contains one IgV domain. While these extracellular domains are fairly similar among SIRPs, their transmembrane and cytoplasmic domains differentiate them from one another. Signal regulatory protein α (SIRPα) is highly expressed on macrophages and dendritic cells. Interaction of the extracellular region of SIRPα with its ligand CD47 elicits signaling and SIRPα phosphorylation. CD47-SIRPα signaling results in the recruitment and activation of the tyrosine phosphatases SHP-1 and SHP-2, which regulate cellular functions in a negative fashion, including the regulation of leukocyte adhesion and transmigration, T cell activation, macrophage fusion and phagocytosis. In addition to its role in "self-signaling", SIRPα also functions as a scaffold for membrane-bound signaling molecules. Interaction of CD47 on tumor cells with SIRPα on tumor-associated macrophages (TAMs) constitutes an innate immune checkpoint that interferes with the detection and phagocytosis. SIRPα V1, SIRPα V2, and SIRPα V8 are the main SIRPα variants in human. hSIRPα V1 is dominant among Europeans, Africans, and South Asians while hSIRPα V2 dominates east Asians. Sequence alignment of hSIRPα V1, hSIRPα V2, and hSIRPα V8 proteins demonstrated the differences within the CD47-binding extracellular Ig-like V-type (IgV) domain.