The two forms of the pituitary adenylate cyclase activating polypeptide (PACAP (1–27) and PACAP (1–38)) interact with distinct receptors on rat pancreatic AR 4‐2J cell membranes

Abstract

The existence of specific receptors for the two PACAPs (Pituirary Adenylate Cyclase Activating Peptides of 27 and 38 amino acids) was previously demonstrated on membranes from the pancreatic acinar cell line AR 4‐2J (Buscail et al., FEBS Lett. 202, 77–81, 1990) by [125I]PACAP‐27 binding. Here we demonstrate, by comparing Scatchard analysis of saturation curves and competition binding curves obtained with [125I]PACAP‐27 and [125I]PACAP‐38 as radioligands, the coexistence of two classes of receptors : 1/ PACAP‐A receptors that recognize PACAP‐27 and PACAP‐38 with the same high affinity (K d 0.3 nM) and 2/ PACAP‐B receptors that recognize PACAP‐38 with a high affinity (K d 0.3 nM) and PACAP‐27 with a lower affinity (K d 30 nM). These two receptors are coupled to adenylate cyclase but can be clearly distinguished by the ability of PACAP(6–27) to specifically inhibit PACAP‐27 adenylate cyclase activation.

Severe microcephaly induced by blockade of vasoactive intestinal peptide function in the primitive neuroepithelium of the mouse.

“…1). Furthermore, PACAP 6-27, a putative PACAP antagonist (22), failed to inhibit embryonic growth (Fig. 1).…”

“…1 and 2 A). Furthermore, PACAP 6-27, a partial PACAP antagonist (22), had no effect on embryonic growth (Fig. 1), suggesting that VA inhibits a specific VIP function not shared by PACAP.…”

Pituitary Adenylate Cyclase-Activating Polypeptide and Its Receptors: 20 Years after the Discovery

“…Type II binding sites, which are abundant in various peripheral organs, including the lung, duodenum, and thymus, possess similar affinity for PACAP and VIP (K d Ϸ 1 nM) Lam et al, 1990). Subtle differences in the ability of PACAP38 and PACAP27 to displace 125 I-PACAP27 from its recognition sites in the CNS suggest that the C-terminal extremity of PACAP must contribute to the binding of the peptide to its receptors (Cauvin et al, 1991;Robberecht et al, 1991b). Likewise, type II binding sites have been subdivided into two classes depending on their affinity for secretin (Hubel, 1972) and helodermin : classic VIP binding sites exhibit low affinity for secretin Robberecht et al, 1982Robberecht et al, , 1988, whereas helodermin-preferring binding sites possess higher affinity for helodermin than for VIP or PACAP and no affinity for secretin (Robberecht et al, 1984(Robberecht et al, , 1988Gourlet et al, 1991a;Shima et al, 1996;Solano et al, 1996;Laburthe and Couvineau, 2002;Laburthe et al, 2007).…”

Localisation of VIP-binding sites exhibiting properties of VPAC receptors in chromaffin cells of rainbow trout (Oncorhynchus mykiss)

“…VIP-binding sites (assumed to be PAC1 or VPAC receptors) were then saturated by incubating sections with solutions containing excess VIP receptor agonist ckVIP (10 -5 ·mol·l -1 chicken VIP; Peninsula Laboratories Inc.), VIP receptor antagonist hVIP 6-28 (10 -5 ·mol·l -1 human VIP 6-28; Peninsula Laboratories Inc.), PACAP receptor agonist hPACAP-27 (10 -5 ·mol·l -1 human PACAP-27; Peninsula Laboratories Inc.) or the PACAP receptor antagonist hPACAP 6-27 (10 -5 ·mol·l -1 human PACAP 6-27; Peninsula Laboratories Inc.) for 2·h each prior to incubation with biotinylated VIP (described above). PACAP 6-27 and VIP 6-28 were chosen on the basis of their potent antagonism of PAC1 (Robberecht et al, 1991;Gaspo et al, 1997) and VPAC receptors (Bodanszky et al, 1973;Fishbein et al, 1994), respectively. Excess amounts were determined from previously established dose-response curves for VIP-and PACAP-elicited secretion of catecholamines (Montpetit and Perry, 2000).…”