ABSTRACT
Experiments were performed on amphibia since by simple observation they could be seen to change their pigmentation in adapting to background color. It was the amphibians which provided the means of measuring melanotropic activity, it was the domestic mammals which were to provide a rich source of the material responsible for their final characterization. After sequence analysis, both peptides were found to be related structurally, possessing the common heptapeptide core sequence Met-Glu-His-Phe-Arg-Trp-Gly which was shown to possess inherent melanotropic activity. The cloning and sequencing of the c-DNA encoding the whole of the ACTH/LPH precursor, finally resolved this fascinating phenomenon. γ-MSH precursor had been identified earlier by Mains and Eipper to be glycosylated and had been termed the 16K fragment, although they did not realize at that time that it contained a melanotropic sequence. While the cloning of this precursor has vastly increased our knowledge of the way in which these peptides are biosynthesized.
