Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide belonging to the vasoactive intestinal polypeptide/glucagon/ secretin family. It is widely distributed in the body, and a variety of biological actions have been reported. Recent studies have shown that there is a family of PACAP receptors (PACAPRs), and two members of this family have been identified. Mouse PACAPR-3 is a protein of 437 amino acids that has 50% and 51% identity with rat PACAP type I and type II receptors, respectively. It binds to vasoactive intestinal polypeptide as well as PACAP-38 and -27, with a slightly higher affinity for PACAP-38, PACAPR-3 mRNA is expressed at high levels in MIN6, at moderate levels in pancreatic islets and other insulin-secreting cell lines, HIT-T15 and RINm5F, as well as in the lung, brain, stomach, and colon, and at low levels in the heart. PACAPR-3 participates in the regulation of insulin secretion. insulin secretion from MIN6 cells is significantly stimulated by PACAP-38.