The?C3a receptor?also known as?complement component 3a receptor 1?(C3AR1) is a?G protein-coupled receptorprotein involved in the?complement system. Receptor for the chemotactic and inflammatory peptide anaphylatoxin C3a. This receptor stimulates chemotaxis, granule enzyme release and superoxide anion production. 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.