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Somatostatin pp 109-121 | Cite as

Proteolytic Events in the Post-Translational Processing of Somatostatin Precursors from Rat Brain Cortex and Anglerfish Pancreatic Islets

  • Paul Cohen
  • Alain Morel
  • Pablo Gluschankof
  • Sophie Gomez
  • Pierre Nicolas
Chapter
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 188)

Abstract

An Arg-Lys esteropeptidase which concerts somatostatin-28 (S-28) into somatostatin-14 (S-14) was detected in rat brain cortical extracts using a synthetic undecapeptide substrate mimicking the octacosapeptide sequence at the restriction site. This enzyme system was unable to release either the octacosapeptide or S-14 from the 15,000 mol wt (15K) rat hypothalamic precursor. This argues in favor of sequential degradation of the precursor into S-14 via S-28 as an obligatory intermediate.

Another in vivo processing system was analyzed in the anglerfish pancreatic Brockmann organs. Here, cloning of two cDNA corresponding to two mRNA species predicts two distinct somatostatins precursors, called prosomatostatins I and II (Hobart et al., Nature 288:137, 1980). While a single S-14 can be detected in extracts made from this pancreatic tissue, indistinguishable from the mammalian species, two S-28 species could be separated by HPLC. Immunochemical and biochemical evidence indicates that the second species should correspond to anglerfish S-28 (AF S-28), the product of prosomatostatin-II processing in vivo. Amino acid analysis, together with the determined complete amino acid sequence of this peptide, demonstrates that this is indeed, the case and that AF S-28 contains in its C-terminal half the [Tyr7,Gly10] derivative of S-14.

These observations give an example of a AFS-28 being a terminal active product of prosomatostatin processing. They suggest that this octacosapeptide, which is potent on the inhibition of growth hormone release by anterior pituitary cells, may play such a role in the gastrointestinal tract of the anglerfish. These results, while not excluding alternative routes, give support to a sequential processing of the 15 K precursor → S-28 → S-14.

Keywords

Growth Hormone Release Anterior Pituitary Cell Complete Amino Acid Sequence Neurosecretory Granule Obligatory Intermediate 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1985

Authors and Affiliations

  • Paul Cohen
    • 1
  • Alain Morel
    • 1
  • Pablo Gluschankof
    • 1
  • Sophie Gomez
    • 1
  • Pierre Nicolas
    • 1
  1. 1.Groupe de Neurobiochimie Cellulaire et MoléculaireUniversité Pierre et Marie Curie Unité Associée au CNRS no 554ParisFrance

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