Reconstitution of the initial steps of mitochondrial protein import

Naomi Hachiya, Katsuyoshi Mihara, Kitaru Suda, Martin Horst, Gottfried Schatz, Trevor Lithgow

Research output: Contribution to journalLetterResearchpeer-review

150 Citations (Scopus)


We have reconstituted the initial steps of mitochondrial protein import with a purified precursor protein, a purified, ATP-dependent, cytosolic chaperone selective for mitochondrial precursors (mitochondrial import stimulating factor; MSF), and either intact mitochondria or intact or solubilized mitochondrial outer membranes. We show 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/Mas22p sub-units of the receptor, and finally delivered to the import channel in the outer membrane. Import in the absence of the MSF bypasses Mas37p/Mas70p. 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.

Original languageEnglish
Pages (from-to)705-709
Number of pages5
Issue number6542
Publication statusPublished - 24 Aug 1995
Externally publishedYes

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