SIRPCD47SIRPalpha
SIRPCD47SIRPalpha refers to the functional interaction between the cell surface receptor Signal Regulatory Protein alpha (SIRPA) and its ligand Cytoglobin Immunoglobulin Domain 47 (CD47), often discussed in the context of the “don’t eat me” signaling mechanism. SIRPA is a transmembrane protein expressed on myeloid cells such as macrophages and neutrophils. Its cytoplasmic domain contains immunoreceptor tyrosine-based inhibitory motifs (ITIMs) that recruit SHP-1 and SHP-2 phosphatases upon phosphorylation. CD47, a ubiquitously expressed transmembrane protein, presents a conserved extracellular IgV-like domain that engages SIRPA with high affinity.
The SIRPA–CD47 axis inhibits phagocytosis and other innate immune effector functions. When CD47 on target cells
Therapeutically, blockade of the SIRPA–CD47 interaction by monoclonal antibodies or small molecules restores macrophage‑mediated tumor clearance