The stimulation of yeast mitochondrial protein synthesis by low molecular weight cytoplasmic factors: requirement for intact mitochondria and lack of effect by folate derivatives.

Protein synthesis by GTP-supplemented yeast mitochondria is stimulated by a fraction of molecular weight less than 2,000 isolated from yeast high-speed supernatant (S-150). The low molecular weight fraction works independently of the respiratory chain as the stimulation effect is not cyanide-sensitive. Stimulation of mitochondrial protein synthesis by cytoplasmic factors is dependent upon the method of mitochondrial isolation. The low molecular weight stimulatory factor(s) are not reduced folate derivatives which supply formyl groups required for initiation of mitochondrial protein synthesis.