The Mitochondrial Protein Import Machinery

Abstract

M itochondria are surrounded by a double-membrane system that defines four intra-organelle compartments: the outer membrane, the inner membrane, the intermembrane space and the matrix. Hundreds of nuclear-encoded mitochondrial proteins are synthesized as precursor proteins in the cytosol and have to be targeted to and imported into the mitochondria. To facilitate this import process, precursor proteins contain targeting and sorting sequences which are recognized and decoded by mitochondrial transloca-tion machineries. This chapter describes the mechanisms by which mitochondrial precursor proteins are targeted to the mitochondria, and sorted into the correct sub-mitochondrial compartment .