Binding and cAMP Studies of Melanotropin Peptides with the Cloned Human Peripheral Melanocortin Receptor, hMC1R

Binding and stimulation of cAMP by the melanotropin peptides α-MSH (α-melanocyte-stimulating hormone) and its superpotent analogues [Nle4, DPhe7] α-MSH (MT-I) and [formula] α-MSH4-10-NH2 (MT-II) were undertaken to examine their respective properties on the human peripheral melanocyte melanocortin receptor, hMC1R. α-MSH was found to possess a binding IC50 value of 6.5 ± 0.9 × 10−9 M and cAMP EC50 value of 2.0 ± 0.6 × 10−9 M. MT-I possesses a binding IC50 value of 1.2 ± 0.3 × 10−9 M and a cAMP EC50 of 0.5 ± 0.03 × 10−9 M. MT-II possesses a binding IC50 of 0.57 ± 0.08 × 10−9 M and cAMP EC50 value of 0.20 ± 0.05 × 10−9 M.