Function
While Humanin exerts neuroprotective and cytoprotective effects in models of Alzheimer’s disease, ischemia, and metabolic stress, reducing apoptosis and improving cell survival7136141, Melanotan I is approved in some regions for prevention of phototoxicity in erythropoietic protoporphyria and is studied as a skin-darkening, photoprotective peptide3444.
Mechanism
While Humanin works as a mitochondrial-derived 24-amino-acid peptide that protects cells against diverse apoptotic insults by interacting with cell-surface cytokine receptor complexes and intracellular targets, thereby activating pro-survival STAT3 and other pathways7136141, Melanotan I is a linear 13-amino-acid analog of α-MSH (afamelanotide) that selectively activates MC1R on melanocytes, increasing eumelanin synthesis and providing photoprotection3444.
Length and Sequence
Humanin is 24 amino acids long, whereas Melanotan I is shorter as it has a length of 13 amino acids. Humanin is made up of a sequence of Methionine, Alanine, Proline, Arginine, Glycine, Phenylalanine, Serine, Cysteine, Leucine, Leucine, Leucine, Leucine, Leucine, Threonine, Serine, Glutamic acid, Isoleucine, Aspartic acid, Leucine, Proline, Valine, Lysine, Arginine, Arginine, Alanine. Melanotan I is made up of a sequence of Serine, Tyrosine, Serine, Nle, Glutamic acid, Histidine, Phenylalanine, Arginine, Tryptophan, Glycine, Lysine, Proline, Valine.