In vitro import of proteins into isolated mitochondria

Import of proteins is of vital importance for the biogenesis of mitochondria. The vast majority of mitochondrial proteins is encoded within the nuclear genome and translocated into various mitochondrial compartments after translation in the cytosol as preproteins. Even in rather primitive eukaryotes like yeasts, these are 700 to 1,000 different proteins, whereas only a handful of proteins is encoded in the mitochondrial DNA. In vitro import studies are important tools to understand import mechanisms and pathways. Using isolated mitochondria and radioactively labeled precursor proteins, it was possible to identify several import machineries and pathways consisting of a large number of components during the last decades.