Receptor for the chemotactic and inflammatory peptide anaphylatoxin C3a. This receptor stimulates chemotaxis, granule enzyme release and superoxide anion production. Interacts with VGF-derived peptide TLQP-21 (By similarity). Widely expressed in several differentiated hematopoietic cell lines, in the lung, spleen, ovary, placenta, small intestine, throughout the brain, heart, and endothelial cells. Mostly expressed in lymphoid tissues. Among the sulfation sites Tyr-174 is essential for binding of C3a anaphylatoxin. O-glycosylated. Belongs to the G-protein coupled receptor 1 family.