title: Intracellular degradation of mitochondrial enzymes.
abstract: Quantitation of the pool of short-lived mitochondrial proteins in cultured cells by a new method shows it to be very low, i.e. approximately 1.35%. Degradation of three long-lived mitochondrial enzymes of rat liver which make up approximately 25-30% of the mitochondrial protein necessitates the cooperation of mitochondrial and lysosomal components. The degradation of carbamyl phosphate synthetase (t1/2, 7.7 d) and of ATPase (t1/2, 2-3 d) requires both a protein component from the inner mitochondrial membrane and lysosomes while degradation of glutamate dehydrogenase (GDH) (t1/2, approximately 1 d) necessitates a mitoplast factor, identified as NADP, which facilitates the inactivation by lysosomes. Chemotropic modification (carbamylation) of GDH also changes stability to rat liver proteases. All three enzymes are synthesized as pro-enzymes. Their processing and possibly control of degradation by maturases as well as the relation of both processes to molecular plasticity is presented.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000378:metabolism*; D004355:Drug Stability; D005969:Glutamate Dehydrogenase / Q000378:metabolism*; D006207:Half-Life; D008025:Ligases / Q000378:metabolism*; D008247:Lysosomes / Q000201:enzymology; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology*; D009249:NADP / Q000494:pharmacology; D011487:Protein Conformation; D051381:Rats; D013367:Submitochondrial Particles / Q000201:enzymology; D013816:Thermodynamics
chemical_list: D009249:NADP; D005969:Glutamate Dehydrogenase; D000251:Adenosine Triphosphatases; D008025:Ligases; D002222:Carbamoyl-Phosphate Synthase (Ammonia)