The preprotein translocase of the mitochondrial outer membrane

The translocase components of the mitochondrial outer membrane (Tom) are essential for the transfer of preproteins from the cytosol to the mitochondria. At least nine Tom components have now been identified and they fall into two categories; receptor components and components of the General Import Pore (GIP). The receptor components most likely diffuse laterally in the membrane and deposit preproteins at the GIP where they are then inserted into the mitochondria. This review focuses on these components and their known interactions in the process of preprotein translocation.