SIRP alpha protein, or Signal regulatory proteinalpha (SIRP-α), also known as Tyrosine protein phosphatase non-receptor type substrate 1, CD172a, Bit, and MyD-1, GenBank Accession No. NM_080792, a.a. 27-370, with C-terminal Avi and His tags, MW 40.3 kDa*. This SIRP alpha protein acts as a receptor for CD47; a.a. 27-370 correspond to the extracellular portion of SIRP-α. *Note: SIRP-α is heavily glycosylated, resulting in higher molecular weight.

CD47 (also known as Rh-associated protein, GP42, integrin-associated protein (IAP), and neurophilin,) is an immunoglobulin-like protein that interacts with its receptor, Signal-regulatory protein alpha (SIRPα), on macrophages. This binding interaction regulates transmigration, oxidative burst cytokine production, and phagocytosis, creating a “don’t eat me" signal. CD47 is ubiquitously expressed on the surface of normal cells, but is overexpressed in numerous cancer cells, where it is thought to contribute to the resistance of tumors to phagocyte-dependent clearance.

Figure 1. Dose response of SIRPa Blocking Antibodies in SIRPɑ/CD47 Dual Effector Reporter Cells.

Figure 2. Dose response of CD47 Blocking Antibody in SIRPɑ/CD47 Dual Effector Reporter Cells.