IMPORT OF RNA INTO MITOCHONDRIA (A REVIEW)

Mitochondria are built of several hundred macromolecules, only a small portion of which are made within the organelle. Most of the mitochond rial proteins are encoded in the nuclear genome, synthesized in the cy toplasm and then imported into the mitochondrion. The RNAs of the prot ein-synthesizing machinery are largely encoded in the mitochondrial ge nome. Recent research has shown that small RNAs are also imported into mitochondria and this process is found in various organisms. However. the mechanisms underlying selective import and RNA translocation acro ss the mitochondrial membrane remain obscure. Development of experimen tal systems for tRNA import into mitochondria made it possible to shed some light on this problem.