VIP/PACAP Receptor Antibodies

Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP) receptors are activated by the endogenous peptides VIP, PACAP-38 and PACAP-27. VPAC1 and VPAC2 receptors display comparable affinity for the PACAP peptides and VIP. Most isoforms of the PAC1 receptor display  >100 fold higher affinity for the PACAP peptides than for VIP. PG 99-465 is a VPAC2 receptor antagonist but has been reported to have significant activity at VPAC1 and PAC1 receptors. The selective PAC1 receptor agonist maxadilan, was extracted from the salivary glands of sand flies and has no sequence homology to VIP or the PACAP peptides. Agonist stimulation normally leads to stimulation of intracellular cyclic AMP accumulation by coupling to Gs proteins. PAC1, VPAC1 and VPAC2 receptors belong to the family B of GPCRs. This family comprises receptors for all peptides structurally related to VIP and PACAP, and also receptors for parathyroid hormone, corticotropin-releasing factor, calcitonin and related peptides. For all family B receptors, the large N-terminal ectodomain plays a crucial role in ligand recognition. Both VIP and PACAP, acting through PAC1 and VPAC2 receptors, play roles in the control of circadian rhythms in the brain's "master clock" in the suprachiasmatic nuclei (SCN) of the hypothalamus. In addition, PAC1 and VPAC2 receptors on pancreatic β-cells have been implicated in the control of pancreatic insulin secretion.