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Scientific article
English

pH-independent and -dependent cleavage of proinsulin in the same secretory vesicle

Published inThe Journal of cell biology, vol. 126, no. 5, p. 1149-1156
Publication date1994
Abstract

By quantitative immunoelectron microscopy and HPLC, we have studied the effect of disrupting pH gradients, by ammonium chloride, on proinsulin conversion in the insulin-producing B-cells of the islets of langerhans. Proinsulin content and pH in single secretory vesicles were measured on consecutive serial sections immunostained alternately with anti-proinsulin or anti-dinitrophenol (to reveal the pH-sensitive probe DAMP) antibodies. Radioactivity labeled proinsulin, proinsulin cleavage intermediates, and insulin were quantitated by HPLC analysis of extracts of islets treated in the same conditions. Cleavage at the C-peptide/A-chain junction is significantly less sensitive to pH gradient disruption than that of the B-chain/C-peptide junction, but the range of pH and proinsulin content in individual vesicles indicate that both cleavages occur in the same vesicle released from the TGN.

Keywords
  • Ammonium Chloride/pharmacology
  • Animals
  • Cytoplasmic Granules/ metabolism
  • Glucose/pharmacology
  • Hydrogen-Ion Concentration
  • Islets of Langerhans/ metabolism
  • Proinsulin/ metabolism
  • Protein Processing, Post-Translational/drug effects
  • Rats
  • Rats, Sprague-Dawley
Citation (ISO format)
ORCI, Lelio et al. pH-independent and -dependent cleavage of proinsulin in the same secretory vesicle. In: The Journal of cell biology, 1994, vol. 126, n° 5, p. 1149–1156. doi: 10.1083/jcb.126.5.1149
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ISSN of the journal0021-9525
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