Biosynthesis of mitochondrial protein components in the liver of cold exposed or adapted rats.

Liver mitochondria of rats exposed or adapted to cold were fractionated after labelling in vivo with radioactive amino acid mixture. Specific activity (Cpm/mg proteins) of unfractionated proteins from the whole mitochondria, water soluble proteins and cytochrome c after the animals exposure to 4 degrees C for 3, 6, 12 and 24 hr was higher as compared with the controls adapted to 24 degrees C; specific activity of contractile and structural proteins was not changed. In rats exposed to cold for 7, 14 and 21 days the labelling of all fractions studied was at the level of controls. The liver weight was increased in cold adapted rats (21 days). If expressed per total liver mass, radioactivity of all fractions was higher in cold adapted rats than in controls.