Human SIRP alpha/CD172a Fluorescein-conjugated Antibody

SIRP alpha (Signal Regulatory Protein alpha), also known as CD172a, SHPS1 and BIT is a variably glycosylated 90-120 kDa member of the SIRP family of proteins.  It is widely expressed, being found on neurons, microglia/macrophages, endothelium, and fibroblasts.  SIRP alpha has a variety of functions, including presynaptic organization, inhibition of integrin action, and induction of myogenesis.  It binds to CD47 and likely other ligands.  Mature human SIRP alpha is a 477 amino acid (aa) type I transmembrane glycoprotein.  It contains an extracellular region (aa 27-372) that shows one V-type Ig-like (aa 32-137) and two C2-type Ig-like domains (aa 147-347).  Its cytoplasmic domain possesses two ITIMs which interact with protein tyrosine phosphatases.  There is one alternative start site at Met102 plus a four aa insertion after Gln421.  Over aa 27-370, human SIRP alpha shares 61% aa identity with mouse SIRP alpha.