Melanotan-2 (MT-2) is a synthetic cyclic heptapeptide (Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂) that acts as a potent nonselective melanocortin receptor agonist. It is used in receptor binding and signal transduction research to investigate MC1R–MC5R pathways ...