Inhibition of the import of mitochondrial proteins by RNase.

RNase treatment of a cell-free translation system prevents transport of mitochondrial precursor proteins from that system into isolated yeast mitochondria. This inhibition depends on the presence of ribosomes in the reticulocyte lysate; if they are cleared by centrifugation, RNase treatment does not specifically inhibit protein uptake by mitochondria. Since protein import can occur in the absence of polyribosomes, RNase treatment does not degrade a structure essential for this process. Rather, the inhibition may be an effect of degraded ribosomes.