Retatrutide (LY3437943) is a synthetic 39-amino acid peptide engineered as a triple receptor co-agonist with simultaneous pharmacological activity at the glucagon-like peptide-1 receptor (GLP-1R), the glucose-dependent insulinotropic polypeptide receptor (GIPR), and the glucagon receptor (GcgR). The compound incorporates non-canonical amino acid substitutions — two alpha-aminoisobutyric acid (Aib) residues and one alpha-methylleucine (alpha-MeLeu) insertion — engineered to resist dipeptidyl peptidase-4 (DPP-4) cleavage, making it a stable tool for in vitro receptor pharmacology.

Research utilizing retatrutide examines the molecular consequences of simultaneous tri-receptor co-activation, particularly the divergent intracellular signaling profiles generated across GLP-1R, GIPR, and GcgR. Active investigation areas include differential cAMP accumulation, beta-arrestin recruitment kinetics, and receptor internalization dynamics measured against single and dual-agonist reference compounds.

Retatrutide is used as a reference compound in structure-activity relationship (SAR) studies, multi-receptor co-agonism pharmacology, and energy homeostasis pathway modeling. Its tri-receptor engagement profile represents a distinct pharmacological tool from dual incretin agonists, enabling comparative mechanistic research across incretin and glucagon signaling axes. All research use is strictly in vitro.