Exendin-4 is a 39-amino-acid peptide studied for its activity at the glucagon-like peptide-1 (GLP-1) receptor. First isolated from the venom of the Gila monster (Heloderma suspectum), exendin-4 shares significant sequence similarity with GLP-1 and binds the GLP-1 receptor with high affinity, making it a standard reference agonist in laboratory studies of incretin biology.

Structure: exendin-4 has the sequence HGEGTFTSDLSKQMEEEAVRLFIEWLKNGGPSSGAPPPS-NH2, with an amidated C-terminus. Compared with GLP-1, exendin-4 has a C-terminal extension that contributes to its resistance to degradation by dipeptidyl peptidase-4 (DPP-4) and to its extended stability in laboratory solutions.

Laboratory applications: cell culture and receptor-binding assays probing GLP-1 receptor signaling (cAMP accumulation readouts), structure-activity studies comparing exendin-4, GLP-1 fragments, and truncated antagonists such as exendin-(9-39), and use as a reference agonist alongside selective antagonist controls. The peptide is also used in assay development and in comparative pharmacology studies of incretin receptor agonists.

Analytical notes: store lyophilized material at -20°C in a desiccator; use freshly prepared solutions and avoid repeated freeze-thaw cycles. Document peptide source, purity, lot number, and storage conditions for all laboratory work.

Disclaimer: This material is supplied for laboratory research use only. It is not intended for human or veterinary use, not for diagnostic or therapeutic use, and not for use as a drug, food, or cosmetic. Researchers must follow institutional safety protocols and applicable regulations.

Citations: Eng J et al., exendin isolation and characterization literature; GLP-1 receptor pharmacology reviews; standard HPLC/MS peptide characterization methods.