SIRP alpha (CD172a, signal-regulatory protein alpha) is a receptor-type transmembrane glycoprotein expressed on cells of myeloid origin, including granulocytes, dendritic cells (DCs), macrophages, mast cells and hematopoietic stem cells. SIRP alpha acts as a substrate for several activated tyrosine kinases, including EGFR, PDGFR, src and insulin receptor and is involved in the negative regulation of receptor tyrosine kinase-coupled signaling pathways. The ligand binding of SIRP alpha to integrin-associated protein CD47 results in tyrosine kinase phosphorylation of immunoreceptor tyrosine-based inhibitory motifs (ITIMs) within the cytoplasmic region of SIRP alpha, which mediates the recruitment and activation of the tyrosine phosphatases SHP-1 and SHP-2. Ligation of SIRP alpha with CD47 has been demonstrated in several regulatory processes, including the inhibition of host cell phagocytosis by macrophages and the bi-directional activation of T cells and DCs. SIRP alpha has regulatory effects on cellular responses induced by serum, growth factors, insulin, oncogenes, growth hormones and cell adhesion, and plays a general role in different physiological and pathological processes. Cancer cells highly express CD47, which activates SIRP alpha and inhibits macrophage-mediated destruction of cancerous cell growth.
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Protein Aliases: Bit; Brain Ig-like molecule with tyrosine-based activation motifs; Brain immunoglobulin like protein with tyrosine - based activation motifs; CD172 alpha; CD172 antigen-like family member A; CD172a; Inhibitory receptor SHPS-1; Macrophage fusion receptor; Macrophage membrane protein MFP150; Protein tyrosine phosphatase non-receptor type substrate 1 (SHP substrate 1); Protein tyrosine phosphatase, non-receptor type substrate 1 (SHP substrate 1); SHP substrate 1; Signal-regulatory protein alpha-1; Sirp-alpha-1; SIRPalpha; SIRPalpha2; Tyrosine-protein phosphatase non-receptor type substrate 1
Gene Aliases: Bit; Mfr; Ptpns1; SHPS-1; Shps1; Sirp; Sirpa
UniProt ID: (Rat) P97710
Entrez Gene ID: (Rat) 25528