MECHANISMS OF PROTEIN IMPORT ACROSS THE MITOCHONDRIAL OUTER-MEMBRANE

Mitochondria import the majority of their proteins from the cytosol. A t the mitochondrial outer membrane, import is initiated through a seri es of reactions, which include preprotein recognition, unfolding, inse rtion anti translocation. These processes are facilitated by a multisu bunit complex, the TOM complex. Specific roles can now be assigned to several components of this complex. Although the import machinery of t he outer membrane can insert and translocate a few proteins on its own , completion of translocation of most preproteins is dependent upon co upling to both the membrane potential and mt-Hsp70/ATP-driven transpor t across the inner membrane, mediated by the TIM complex.