Truncated exendin-3 peptide, potent and selective glucagon-like peptide-1 receptor (GLP-1R) antagonist. Exendin-3 shares homology with vasoactive intestinal peptide (VIP), secretin, helospectin I and II and helodermin. Exendin-3 stimulates the increases in cellular cAMP levels and amylase release from pig pancreatic cells.

Exendins are a group of peptide hormones of the glucagon superfamily. Exendins stimulate insulin secretion in response to rising blood glucose levels, and modulate gastric emptying to slow the entry of ingested sugars into the bloodstream. Exendin-3 was originally isolated from the Mexican beaded lizard (Heloderma horridum) venom gland