Exendin-4 (5-39) is an antagonist of glucagon-like peptide 1 (GLP-1) receptors. GLP-1 is a G protein-coupled receptor (GPCR) that shares sequence identity with other Family B receptors such as those for secretin, glucagon, and vasoactive intestinal peptide. Unlike the full length exendin-4, a GLP-1 agonist, exendin (5-39) antagonizes GLP-1 stimulated insulin release after food intake. Exendin (5-39) also modulates synaptic transmission via glutamate uptake in the dentate gyrus and improves memory impairment in beta-amyloid protein-treated rats.
