Bradykinin receptor B1. BDKRB1 gene encodes a protein that is one of two Bradykinin receptors. The bradykinin receptor family is a group of G-protein coupled receptors whose principal ligand is the protein bradykinin. This gene encodes a receptor for bradykinin B1. The 9 aa bradykinin peptide elicits many responses including vasodilation, edema, smooth muscle spasm and pain fiber stimulation. This receptor associates with G proteins that stimulate a phosphatidylinositol-calcium second messenger system.