[Induction of cytosolic proteins controlling mitochondrial protein synthesis by thyroid hormone].

The effect of thyroid hormone on the generation of modulators of mitochondrial protein synthesis was investigated. The modulators were present in the 150,000 X g supernatant (S-150) prepared from Wistar rat liver and kidney. A stimulator was found in the liver, and an inhibitory modulator was present in kidney tissue. Generation of these modulators was stimulated by T4 administration to the animals. Both the stimulatory and inhibitory modulators were inactivated by pretreatment with trypsin or boiling. The molecular weight of these modulators was estimated by gel filtration study and for both the stimulatory and inhibitory modulator proteins was approximately 10,000 daltons. The results suggested that thyroid hormone regulates mitochondrial protein synthesis through the stimulation of synthesis of mitochondrial protein synthesis modulators, and that the tissue specific modulators (stimulatory in liver and inhibitory in kidney) can be produced by the hormone.