Exendin-3 is a biologically active peptides isolated from venoms of the Gila monster lizards, Heloderma horridurn . VIP receptor, putative exendin receptor[1]
Exendin-3 interacts with at least two receptors on guinea pig pancreatic acini; at high concentrations (>100 nM) the peptide interacts with VIP receptors, thereby causing a large increase in cAMP and stimulating amylase release; at lower concentrations (0.1-3 nM) the peptide interacts with a putative exendin receptor, thereby causing a smaller increase in cAMP of undetermined function[1].
[1]. Raufman JP, et al. Exendin-3, a novel peptide from Heloderma horridum venom, interacts with vasoactive intestinal peptide receptors and a newly described receptor on dispersed acini from guinea pig pancreas. Description of exendin-3(9-39) amide, a specific exendin receptor antagonist. J Biol Chem. 1991 Feb 15;266(5):2897-902.