On the cell-free system of protein synthesis from mammalian mitochondria

Some properties of a submitochondrial cell-free system for protein synthesis are described. The system was prepared from rat liver mitochondria lysed with Triton X-100, and the lysate was characterized by a linear rate of [14C]amino acid incorporation for 15-20 min with subsequent decline in activity. The incorporation reaction was inhibited by chloramphenicol and was insensitive to cycloheximide. Poly(U) addition stimulated [14CA1phenylalanine incorporation by the preincubated submitochondrial system. Upon the addition of 7.5S mRNA that was isolated from mitochondria the major translation product was identified as a hydrophobic poly-peptide which in some properties (solubility in chloroform-methanol mixture) was similar to one of polypeptides synthesized by the sub-mitochondrial system on endogeneous mRNAs.