Protein degradation in mitochondria

The biogenesis of mitochondria and the maintenance of mitochondrial functio ns depends on an autonomous proteolytic system in the organelle which is hi ghly conserved throughout evolution. Components of this system include proc essing peptidases and ATP-dependent proteases, as well as molecular chapero ne proteins and protein complexes with apparently regulatory functions. Whi le processing peptidases mediate maturation of nuclear-encoded mitochondria l preproteins, quality control within various subcompartments of mitochondr ia is ensured by ATP-dependent pretenses which selectively remove non-assem bled or misfolded polypeptides. Moreover; these proteases appear to control the activity- or steady-state levels of specific regulatory proteins and t hereby ensure mitochondrial genome integrity, gene expression and protein a ssembly.