title: Detection and partial characterization of proopiomelanocortin-related end-products from the pars intermedia of the toad, Bombina orientalis.
abstract: Steady-state analyses were performed on the proopiomelanocortin (POMC)-related end-products present in acid extracts of the pars intermedia of the anuran amphibian, Bombina orientalis. Sephadex G-75 gel filtration chromatography indicated that immunoreactive alpha-MSH-sized material and N-acetylated beta-endorphin-related material are the major POMC-related products present in this tissue. The alpha-MSH-sized immunoreactivity was further fractionated by reversed phase HPLC. The major peak of immunoreactivity isolated by this procedure eluted with the same retention time as synthetic ACTH(1-13)amide. Cation exchange chromatography supported the conclusion that the major storage form of alpha-MSH in the pars intermedia of Bombina is ACTH(1-13)amide. Analysis of Bombina pars intermedia in culture indicated that mono-acetylated and di-acetylated alpha-MSH were the major forms of alpha-MSH secreted into the medium. The major peak of N-acetylated beta-endorphin-related material was further analyzed by cation exchange chromatography and Sephadex G-25 gel filtration column chromatography. The major storage form of beta-endorphin in this tissue is N-acetylated, has a net positive charge at pH 2.75 of +1, and has an apparent molecular weight of 1.2K. The beta-endorphin present in the pars intermedia of this tissue does not undergo further N-acetylation at the time of secretion. These results indicate that in the pars intermedia of the archaeobatrachian, Bombina orientalis, the N-acetylation of alpha-MSH is a cosecretory processing event, whereas N-acetylation of beta-endorphin is a post-translational processing event. These results are compared to other archaeobatrachian and neobatrachian pituitary POMC systems that have been analyzed.
authors.affiliation: Department of Biological Sciences, University of Denver, Colorado 80208.
authors.forename: R M
authors.initials: RM
authors.lastname: Dores
authors.forename: T
authors.initials: T
authors.lastname: Truong
authors.forename: T C
authors.initials: TC
authors.lastname: Steveson
mesh_terms: D000818:Animals; D001001:Anura / Q000502:physiology*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D005260:Female; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000096:biosynthesis* / Q000737:chemistry* / Q000302:isolation & purification; D010446:Peptide Fragments / Q000096:biosynthesis* / Q000737:chemistry* / Q000302:isolation & purification; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011333:Pro-Opiomelanocortin / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011863:Radioimmunoassay; D000521:alpha-MSH / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D001615:beta-Endorphin / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D010446:Peptide Fragments; D000521:alpha-MSH; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin; C035101:N-acetyl-beta-endorphin; D009074:Melanocyte-Stimulating Hormones