Beta-endorphin-related peptides in the pituitary gland: isolation, identification and distribution

D G Smyth, S Zakarian, J F Deakin, D E Massey

Research output: Contribution to journalArticlepeer-review

Abstract

A new procedure is described for isolation of four forms of beta-endorphin from bovine pituitary. The four peptides are: the C-fragment of lipotropin (bovine lipotropin residues 63-93, or beta-endorphin, the alpha, N-acetyl derivative of the C-fragment, the C'-fragment (bovine lipotropin residues 63-89) and the alpha, N-acetyl derivative of the C'-fragment. Of these peptides, beta-endorphin alone possesses potent analgesic activity. The procedure has been applied in studying the distribution of beta-endorphin-related peptides in two regions of the pituitary. The results show that in the anterior pituitary of the pig and the rat, beta-endorphin is produced with a high degree of specificity in its opiate active form. In contrast, in the pars intermedia of both species at least six peptides related to beta-endorphin are elaborated and beta-endorphin represents only a minor component. The principal peptides in the pars intermedia have been identified as acetylated derivatives of lipotropin C'-fragment: in the pig the predominant peptide is alpha,N-acetyl C'-fragment and in the rat the major peptide appears to be an epsilon-acetylated derivative of alpha,N-acetyl C'-fragment. Thus, beta-endorphin is activated in the anterior pituitary and inactivated in the pars intermediate. The results demonstrate selective and specific processing of the 31K ACTH-endorphin prohormone in the different regions of the pituitary. In the anterior pituitary two biologically active peptides, ACTH and beta-endorphin, are generated together; in the pars intermedia alpha-melanotropin (alpha-MSH) is accompanied by forms of beta-endorphin that have been inactivated by acetylation and proteolysis.

Original languageEnglish
Pages (from-to)79-96
Number of pages18
JournalCiba Foundation symposium
Volume81
Publication statusPublished - 1981

Keywords

  • Analgesia
  • Animals
  • Biological Assay
  • Cattle
  • Chromatography, Gel
  • Chromatography, Ion Exchange
  • Endorphins
  • Organ Specificity
  • Pituitary Gland
  • Pituitary Hormones, Anterior
  • Pro-Opiomelanocortin
  • Protein Precursors
  • Rats
  • beta-Endorphin
  • Journal Article

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