Induction of carbamoyl-phosphate synthetase I in Reuber hepatoma H-35 by dexamethasone.
Reuber hepatoma H-35 was found to retain the activity of carbamoyl-phosphate synthetase I. The content of this enzyme in H-35 grown in Eagle's minimal essential medium was about half that in rat liver. The enzyme from H-35 was the same as that from rat liver in molecular weight estimated by SDS-polyacrylamide gel electrophoresis, specific enzyme activity, kinetic parameters for ATP and N-acetyl-L-glutamate, and immunological crossreactivity. The enzyme in H-35 was induced by dexamethasone (1.4-fold) but not by glucagon or dibutyryl cAMP. Incorporation of [35S] methionine into the enzyme indicated that the effect of dexamethasone was due to increased synthesis of the enzyme protein (2.1-fold). By labeling with [35S]methionine, the precursor and the mature forms of carbamoyl-phosphate synthetase I were observed in the post-mitochondrial and mitochondrial fractions, respectively. By chasing the labeled cells with unlabeled methionine and cycloheximide, it was observed that the rate of translocation of the precursor into mitochondria is not affected by dexamethasone.
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000096:biosynthesis*; D003907:Dexamethasone / Q000494:pharmacology*; D004790:Enzyme Induction; D005934:Glucagon / Q000494:pharmacology; D008025:Ligases / Q000096:biosynthesis*; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008114:Liver Neoplasms, Experimental / Q000201:enzymology*; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains
D003994:Bucladesine; D003907:Dexamethasone; D005934:Glucagon; D008025:Ligases; D002222:Carbamoyl-Phosphate Synthase (Ammonia)