The frog pars intermedia contains only the non-acetylated form of alpha-MSH: acetylation to generate alpha-MSH occurs during the release process.
Pulse-chase experiments revealed that the frog pars intermedia synthesizes the desacetyl form of alpha-MSH. Its structure was shown to be similar, if not identical, to the mammalian structure. During release two additional peptides derived from desacetyl alpha-MSH appeared, one being alpha-MSH. We conclude that the N-acetylation of newly synthesized MSH is associated with release of the hormone. Radioimmunoassays and bioassays showed that the non-acetylated peptide is the only tissue form of MSH and confirmed that acetylation is linked to release.
D000107:Acetylation; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D009074:Melanocyte-Stimulating Hormones / Q000235:genetics* / Q000302:isolation & purification; D010446:Peptide Fragments / Q000032:analysis; D010902:Pituitary Gland / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011895:Rana ridibunda
D010446:Peptide Fragments; D009074:Melanocyte-Stimulating Hormones