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Scientific article
English

Insulin, not C-peptide (proinsulin), is present in crinophagic bodies of the pancreatic B-cell

Published inThe Journal of cell biology, vol. 98, no. 1, p. 222-228
Publication date1984
Abstract

We have obtained evidence by autoradiography and immunocytochemistry that mature secretory granules of the pancreatic B-cell gain access to a lysosomal compartment (multigranular or crinophagic bodies) where the secretory granule content is degraded. Whereas the mature secretory granule content shows both insulin and C-peptide (proinsulin) immunoreactivities, in crinophagic bodies only insulin, but not C-peptide, immunoreactivity was detectable. The absence of C-peptide (proinsulin) immunoreactivity in multigranular bodies, i.e., in early morphological stages of lysosomal digestion, was compatible with the ready access and breakdown of C-peptide and/or proinsulin by lysosomal degrading enzymes, while the insulin crystallized in secretory granule cores remained relatively protected. However, in the final stage of lysosomal digestion, i.e., in residual bodies where the secretory granule core material is no longer present, insulin immunoreactivity became undetectable. Lysosomal digestion thus appears to be a normal pathway for insulin degradation in the pancreatic B-cell.

Keywords
  • Animals
  • C-Peptide/metabolism
  • Cell Compartmentation
  • Cytoplasmic Granules/metabolism
  • Immunologic Techniques
  • Insulin/ metabolism
  • Islets of Langerhans/ metabolism/ultrastructure
  • Lysosomes/metabolism
  • Microscopy, Electron
  • Proinsulin/ metabolism
  • Rats
Citation (ISO format)
ORCI, Lelio et al. Insulin, not C-peptide (proinsulin), is present in crinophagic bodies of the pancreatic B-cell. In: The Journal of cell biology, 1984, vol. 98, n° 1, p. 222–228. doi: 10.1083/jcb.98.1.222
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ISSN of the journal0021-9525
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