C3aR
C3aR (C3a anaphylatoxin receptor, CD88a) is a seven-transmembrane G protein-coupled receptor that detects C3a, the anaphylatoxin released when complement C3 is cleaved during activation. Ligand binding couples mainly to Gi family proteins, triggering calcium mobilization, chemotaxis, degranulation and cytokine release in mast cells, eosinophils, monocytes, T cells and non-hematopoietic cells such as endothelium and astrocytes. Through these responses C3aR shapes allergic inflammation, ischemia-reperfusion injury, sepsis and autoimmune pathology, and it also modulates synaptic pruning in the nervous system. Distinct from the opsonin receptors CR1-CR4, C3aR mediates soluble-fragment signaling, and selective C3aR antagonists are in preclinical and clinical development as anti-inflammatory agents.
