ABSTRACT
Mitochondrial L-3-glycerophosphate dehydrogenase (EC 1.1.99.5) is synthesised in bovine kidney (NBL-1) cells treated with uncoupler as a cytosolic precursor with Mr = 76,000 indistinguishable from the mature form. In vitro translation of rat liver mRNA also gives rise to a product of Mr = 76,000 but when this is imported into mitochondria it is processed to a product of Mr = 66,000. L-3-Glycerophosphate dehydrogenase activity and immunoreactive protein are greatly decreased in liver mitochondria from hypothyroid rats. Paradoxically, in vitro translation of the mRNA from such animals gives rise to large amounts of the protein, much greater than that synthesised from euthyroid mRNA and comparable with that produced from hyperthyroid mRNA.
Subject(s)
Glycerolphosphate Dehydrogenase/genetics , Hypothyroidism/enzymology , Mitochondria, Liver/enzymology , Mitochondria/enzymology , Protein Biosynthesis , Transcription, Genetic , Animals , Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone/pharmacology , Cattle , Cell Line , Glycerolphosphate Dehydrogenase/metabolism , Kidney/enzymology , Male , NADH Dehydrogenase/metabolism , Propylthiouracil/pharmacology , Protein Processing, Post-Translational , Rats , Rats, Inbred Strains , Reference Values , Submitochondrial Particles/enzymologyABSTRACT
Mitochondrial NADH dehydrogenase from a variety of rat tissues was isolated by immunoprecipitation with an antiserum to the bovine heart enzyme. The subunit composition of the enzyme from liver, kidney and lung differed from that present in heart, brain and skeletal muscle by the absence of an Mr 18,500 protein and the absence of an Mr 17,000 protein, suggesting the existence of tissue-specific isoenzymes.
