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Cooperation of lysosomes and inner mitochondrial membrane in the degradation of carbamoyl phosphate synthetase and other proteins

Authors
Journal
Biochimica et Biophysica Acta (BBA) - General Subjects
0304-4165
Publisher
Elsevier
Publication Date
Volume
1034
Issue
3
Identifiers
DOI: 10.1016/0304-4165(90)90049-3
Keywords
  • Proteinase
  • Proteolysis
  • Lysosome
  • Carbamoyl Phosphate Synthetase
  • Mitochondrion
Disciplines
  • Biology

Abstract

Abstract Carbamoyl phosphate synthetase (CPS) from rat liver is proteolitically inactivated at acid pH by broken lysosomes. Inactivation increases when lysosomes are previously incubated with inner mitochondrial membrane, although this mitochondrial fraction does not inactivate CPS ‘per se’. The increased degradation is due to membrane factor(s), most probably mitochondrial proteinase(s), solubilized by lysosomal matrix proteinases, after incubation of the inner mitochondrial membrane fraction with broken lysosomes. This (these) factor(s) degrade(s) CPS and other proteins in the absence of lysosomal proteinases or when these are inhibited by leupeptin, chymostatin and pepstatin. We have also tested the possible regulation of this degradation and found that ATP and, particularly, acetyl glutamate accelerate the degradation of CPS by the factor(s) liberated from the inner mitochondrial membrane.

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