Moving proteins from the cytosol into mitochondria.
Mitochondria of the yeast Saccharomyces cerevisiae contain at least 750 different proteins, which perform diverse roles. Most of these proteins (approx. 99%) are translated on cytosolic ribosomes, and their import into mitochondria is essential for mitochondrial function. Proteinaceous machineries of great complexity, the so-called translocases, in the mitochondrial membranes mediate the import of these proteins.