Integrating mitochondrial translation into the cellular context.

Mitochondrial-encoded subunits of the oxidative phosphorylation system assemble with nuclear-encoded subunits into enzymatic complexes. Recent findings showed that mitochondrial translation is linked to other mitochondrial functions, as well as to cellular processes. The supply of mitochondrial-encoded proteins is coordinated by the coupling of mitochondrial protein synthesis with assembly of respiratory chain complexes. MicroRNAs imported from the cytoplasm into mitochondria were, surprisingly, found to act as regulators of mitochondrial translation. In turn, translation in mitochondria controls cellular proliferation, and mitochondrial ribosomal subunits contribute to the cytoplasmic stress response. Thus, translation in mitochondria is apparently integrated into cellular processes.