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EMBO Rep. 2008 Jun;9(6):548-54. doi: 10.1038/embor.2008.49. Epub 2008 Apr 18.

Assembly of the three small Tim proteins precedes docking to the mitochondrial carrier translocase.

Author information

1
Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Freiburg, Germany.

Abstract

The mitochondrial intermembrane space contains a family of small Tim proteins that function as essential chaperones for protein import. The soluble Tim9-Tim10 complex transfers hydrophobic precursor proteins through the aqueous intermembrane space to the carrier translocase of the inner membrane (TIM22 complex). Tim12, a peripheral membrane subunit of the TIM22 complex, is thought to recruit a portion of Tim9-Tim10 to the inner membrane. It is not known, however, how Tim12 is assembled. We have identified a new intermediate in the biogenesis pathway of Tim12. A soluble form of Tim12 first assembles with Tim9 and Tim10 to form a Tim12-core complex. Tim12-core then docks onto the membrane-integrated subunits of the TIM22 complex to form the holo-translocase. Thus, the function of Tim12 in linking soluble and membrane-integrated subunits of the import machinery involves a sequential assembly mechanism of the translocase through a soluble intermediate complex of the three essential small Tim proteins.

PMID:
18421298
PMCID:
PMC2427372
DOI:
10.1038/embor.2008.49
[Indexed for MEDLINE]
Free PMC Article
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