Protein synthesis in isolated thyroid mitochondria

Amino acid incorporation into sheep thyroid mitochondria was reassessed since the only previous results on the subject showed some contradictions with most data obtained with rat liver mitochondria. The incorporation of leucine or of a mixture of amino acids into thyroid mitochondria was linear up to 90 min. Leucine concentration in the incubation medium was an important rate limiting factor of thyroid mitochondrial protein synthesis. Chloramphenicol, puromycin and ethidium bromide were strong inhibitors, while RNAase, actinomycin D, rifampicin and cycloheximide did not exert any inhibitory effect on amino acid incorporation. Addition of various inhibitors and uncouplers of mitochondrial metabolism further showed that optimal mitochondrial protein synthesis required intact electron transport, and oxidative phophorylation, and exogenous substrate and phosphate, while the endogenous pool of adenine nucleotides seemed to be selfsufficient. © 1972 by The Endocrine Society.SCOPUS: ar.j