Fig. 1
From: PACAP and its receptors in cranial arteries and mast cells
Schematic overview of selectivity of receptors for pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP). Pituitary adenylate cyclase activating polypeptide receptor 1 (PAC1) has a 1000-fold greater affinity for PACAP1–27 (red) and PACAP1–38 (yellow) than for VIP (light blue). Vasoactive intestinal peptide receptor (VPAC)1 and VPAC2 bind VIP (blue) and PACAP1–27(red) and PACAP1–38 (yellow) with equal affinity. pKi (negative logarithm of the concentration that occupies half the receptor population at equilibrium) values given in the figure is adapted from [19]. No difference in receptor selectivity between PACAP1–38 and PACAP1–27 is described