Document Detail

Inhibition of pyruvate carboxylase degradation and total protein breakdown by lysosomotropic agents in 3T3-L1 cells.
MedLine Citation:
PMID:  6347183     Owner:  NLM     Status:  MEDLINE    
1. Exposure to [3H]biotin during the differentiation of 3T3-L1 cells to adipocytes selectively labelled pyruvate carboxylase (EC A subsequent incubation of labelled cells permitted the measurement of the degradation rate constant of this mitochondrial enzyme. 2. In medium without serum, pyruvate carboxylase was degraded with a half-life of 64 h, considerably longer than that found for average cell protein. The long half-life is commensurate with the enzyme being catabolized when whole mitochondria are destroyed. 3. The breakdown of pyruvate carboxylase was inhibited to a greater extent than the breakdown of total cell protein by insulin, NH4Cl and inhibitors of lysosomal proteinases, suggesting that the enzyme is degraded by the autophagic lysosomal system of the cell. 4. The above evidence implies that whole mitochondria are degraded in lysosomes, a conclusion that agrees with earlier electron-microscopic evidence showing mitochondria within autophagic vacuoles. 5. A second degradative pathway must be invoked to account for the breakdown of mitochondrial proteins of short half-life.
C S Chandler; F J Ballard
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Biochemical journal     Volume:  210     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  1983 Mar 
Date Detail:
Created Date:  1983-08-11     Completed Date:  1983-08-11     Revised Date:  2010-09-10    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  845-53     Citation Subset:  IM    
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MeSH Terms
Adipose Tissue / cytology,  drug effects,  metabolism*
Ammonium Chloride / pharmacology
Biotin / metabolism
Cells, Cultured
Cycloheximide / pharmacology
Electrophoresis, Polyacrylamide Gel
Insulin / pharmacology
Lysosomes / metabolism*
Proteins / metabolism*
Pyruvate Carboxylase / antagonists & inhibitors*
Reg. No./Substance:
0/Proteins; 11061-68-0/Insulin; 12125-02-9/Ammonium Chloride; 58-85-5/Biotin; 66-81-9/Cycloheximide; EC Carboxylase

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