Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide belonging to the vasoactive intestinal polypeptide/glucagon/secretin family. PACAP is widely distributed in the body and is involved in a variety of biological reactions. Several PACAP receptors (PACAPRs) have been identified. Mouse PACAPR-3 (VIP Receptor 2) is a 437-amino acid protein that has 50% and 51% identity with rat PACAP type I and II receptors respectively. PACAPR-3 binds to vasoactive intestinal polypeptide (VIP) as well as PACAP-27 and -38. PACAPR-3 participates in the regulation of insulin secretion. The activity of the receptor is mediated by G-proteins which activate adenylyl cyclase.