Function
While Melanotan I is approved in some regions for prevention of phototoxicity in erythropoietic protoporphyria and is studied as a skin-darkening, photoprotective peptide3444, PT-141 is FDA-approved for treatment of hypoactive sexual desire disorder in premenopausal women and is studied for sexual dysfunction in other populations, increasing sexual desire via CNS melanocortin pathways42101.
Mechanism
While Melanotan I works as a linear 13-amino-acid analog of α-MSH (afamelanotide) that selectively activates MC1R on melanocytes, increasing eumelanin synthesis and providing photoprotection3444, PT-141 is the synthetic melanocortin receptor agonist bremelanotide, an analog of α-MSH that activates central MC3R and MC4R to modulate neuronal circuits governing sexual desire and arousal3242101.
Length and Sequence
Melanotan I is 13 amino acids long, whereas PT-141 is shorter as it has a length of 7 amino acids. Melanotan I is made up of a sequence of Serine, Tyrosine, Serine, Nle, Glutamic acid, Histidine, Phenylalanine, Arginine, Tryptophan, Glycine, Lysine, Proline, Valine. PT-141 is made up of a sequence of sequence data not available in the current dataset.