In vitro biosynthesis and chemical characterization of beta-lipotropin, gamma-lipotropin, and beta-endorphin in rat pars intermedia.

AUTOR(ES)

Seidah, N G

RESUMO

Three 3-hr incubations of pars intermedia cells from 40 rat pituitaries with [35S]methionine, [3H]lysine, and [3H]leucine sufficed for the identification and chemical characterization of biosynthesized beta-lipotropin, gamma-lipotropin, and beta-endorphin. From the molecular weight, migration on polyacrylamide gels, and sequence Met5, Lys9, Leu14,17, rat beta-endorphin was shown to be identical to its sheep homologue and no trace of Leu5 beta-endorphin could be detected. Rat beta-lipotropin differs from that of sheep in its elution properties on CM-cellulose, and its sequence shows Leu2,10,14, Lys20. Rat gamma-lipotropin shows the same NH2-terminal sequence as beta-lipotropin and is again different from its sheep homologue. The identification of rat beta-lipotropin was confirmed by its selective cleavage into beta-endorphin after trypsin digestion of the citraconylated peptide, a property not observed with rat gamma-lipotropin.

Documentos Relacionados

• Biosynthesis of beta-endorphin from beta-lipotropin and a larger molecular weight precursor in rat pars intermedia.
• In vitro biosynthesis of beta-endorphin, gamma-lipoprotein, and beta-lipotropin by the pars intermedia of beef pituitary glands.
• Concomitant synthesis of beta-endorphin and alpha-melanotropin from two forms of pro-opiomelanocortin in the rat pars intermedia.
• Conformation of beta-endorphin and beta-lipotropin: formation of helical structure in methanol and sodium dodecyl sulfate solutions.
• beta-Lipotropin is the major opioid-like peptide of human pituitary and rat pars distalis: lack of significant beta-endorphin.