Temperature dependence of protein degradation, autophagic sequestration and mitochondrial sugar uptake in rat hepatocytes

Paul B. Gordon, Attila L. Kovacs, Per O. Seglen

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Lysosomal (propylamine-sensitive) protein degradation as well as the energy-dependent (chymostatin-sensitive) part of the non-lysosomal protein degradation was found to be strongly affected by temperature in isolated rat hepatocytes, the activation energy (Ea) being about 25 kcal/mol for both processes. In contrast, the energy-independent (chymostatin-resistant) part of the non-lysosomal degradation had an Ea of approx. 10 kcal/mol only. Sequestration of electroinjected [14C]sucrose into sedimentable organelles showed a pronounced temperature dependence. By means of digitonin extraction it was possible to distinguish between a moderately temperature-sensitive mitochondrial sugar uptake (Ea approx. 12 kcal/mol) and a strongly temperature-dependent autophagic sequestration (Ea approx. 22 kcal/mol). There was no significant autophagic sequestration below 20°C. The sequestration process is more temperature-sensitive than, for example, the early steps of endocytosis, and is likely to represent the major controlling step in the overall autophagic-lysosomal pathway.

Original languageEnglish
Pages (from-to)128-133
Number of pages6
JournalBBA - Molecular Cell Research
Volume929
Issue number2
DOIs
Publication statusPublished - Jul 6 1987

Keywords

  • (Rat hepatocyte)
  • Autophagic sequestration
  • Protein degradation
  • Sugar uptake
  • Temperature dependence

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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