Alternative titles; symbols
Hachiya et al. (1995) noted that the import of many proteins into mitochondria is initiated by the interaction of the amino-terminal targeting sequence with mitochondrial import-stimulating factor (MSF), which selectively binds mitochondrial precursor proteins. This interaction causes MSF to hydrolyze ATP. The MSF-precursor complex can bind to outer membrane vesicles from rat liver mitochondria with concomitant inhibition of ATPase activity. Hachiya et al. (1995) identified the mitochondrial proteins that recognized the MSF-bound precursor in yeast. They reconstituted the initial steps of yeast mitochondrial protein import with a purified precursor protein, a purified ATP-dependent cytosolic chaperone selective for mitochondrial precursors, namely MSF, and either intact mitochondria or intact or solubilized mitochondrial outer membranes. They showed that the precursor-MSF complex first binds to the Mas37p/Mas70p subunits of the mitochondrial import receptor. After ATP-dependent release of MSF, the precursor is transferred from Mas37p/Mas70p to the Mas20p (601848)/Mas22p subunits of the receptor, and finally delivered to the import channel in the outer membrane. The import in the absence of the MSF bypasses Mas37p/Mas70p. Hachiya et al. (1995) stated that the ATP-mediated transfer of a precursor from MSF to specific subunits of the import receptor is similar to the GTP-mediated transfer of precursors from the signal recognition particle to its receptor on the endoplasmic reticulum.
Hachiya, N., Mihara, K., Suda, K., Horst, M., Schatz, G., Lithgow, T. Reconstitution of the initial steps of mitochondrial protein import. Nature 376: 705-709, 1995. [PubMed: 7651521] [Full Text: https://doi.org/10.1038/376705a0]