Mitochondrial protein synthesis in Chinese hamster cells (line CHO) synchronized by isoleucine deprivation

Mitochondrial protein synthesis was measured in line CHO cells after phases of the cell cycle were synchronized by isoleucine deprivation or mitotic selection. Maximum incorporation of [3H] leucine into mitochondrial polypeptides occurred within 2 hours after isoleucine was added to initiate G1 traverse. In cells synchronized in G1 by mitotic selection, the rate of mitochondrial protein synthesis was fairly constant throughout the cell cycle. SDS-polyacrylamide gel electrophoretic profiles of labeled mitochondrial polypeptides were similar in cells synchronized by either isoleucine deprivation or mitotic selection. Obvious changes in the distribution of polypeptides were not detected during various phases of the cell cycle. The increased rate of incorporation of [3H] leucine into mitochondrial polypeptides after reversal of G1-arrest may indicate that mitochondrial protein synthesis and possibly mitochondrial biogenesis are synchronized in CHO cells deprived of isoleucine.