In vitro synthesis of ACTH- and beta-endorphin-related substances in the pars distalis of Anolis carolinensis.
In order to investigate the biosynthesis of ACTH- and beta-endorphin-related substances in the pars distalis of Anolis carolinensis, explants of pars distali were incubated for 24 hr in a complete medium which contained [3H]tyrosine. Acid extracts of the incubates were immunoprecipitated with either an affinity-purified ACTH antiserum or an affinity-purified beta-endorphin antiserum and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Three distinct peaks of ACTH-related material were detected. The major peak comigrated with human ACTH(1-39), while two minor peaks corresponded in apparent molecular weight to ACTH biosynthetic intermediate and precursor-sized material. Three peaks of beta-endorphin-related material were also detected. The major peak comigrated with beta-endorphin(1-31), while two minor peaks corresponded to beta-lipotropin (LPH) and precursor-sized material. Sequential immunoprecipitation experiments indicated that the precursor-sized material had antigenic determinants for both ACTH and beta-endorphin. In addition this peak was identical in apparent molecular weight to the common precursor for alpha-melanocyte-stimulating hormone (alpha-MSH) and beta-endorphin in the pars intermedia of A. carolinensis (R.M. Dores, Peptides 3, 925-935). Analysis of extracts of reptile pars distalis by gel-filtration chromatography revealed a single peak of naloxone-reversible opiate bioactivity which coeluted with the peak of beta-endorphin-sized immunoreactivity. On a molar basis there is tenfold more opiate bioactivity in the reptile pars distalis than in the reptile pars intermedia.
D000324:Adrenocorticotropic Hormone / Q000096:biosynthesis*; D000818:Animals; D001681:Biological Assay; D002850:Chromatography, Gel; D004723:Endorphins / Q000096:biosynthesis*; D066298:In Vitro Techniques; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011333:Pro-Opiomelanocortin / Q000378:metabolism; D012104:Reptiles / Q000378:metabolism*; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism; D001615:beta-Endorphin
D004723:Endorphins; D009270:Naloxone; D014443:Tyrosine; D001615:beta-Endorphin; D011333:Pro-Opiomelanocortin; D000324:Adrenocorticotropic Hormone