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Different import pathways through the mitochondrial intermembrane space for inner membrane proteins
Author(s) -
Leuenberger Danielle,
Bally Nikolaus A.,
Schatz Gottfried,
Koehler Carla M.
Publication year - 1999
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/18.17.4816
Subject(s) - intermembrane space , translocase of the inner membrane , mitochondrial intermembrane space , translocase of the outer membrane , biology , mitochondrial membrane transport protein , mitochondrial carrier , inner membrane , inner mitochondrial membrane , microbiology and biotechnology , protein targeting , membrane protein , transport protein , integral membrane protein , mitochondrion , biochemistry , membrane transport protein , bacterial outer membrane , membrane , gene , escherichia coli
Earlier work on the protein import system of yeast mitochondria has identified two soluble 70 kDa protein complexes in the intermembrane space. One complex contains the essential proteins Tim9p and Tim10p and mediates transport of cytosolically‐made metabolite carrier proteins from the outer to the inner membrane. The other complex contains the non‐essential proteins Tim8p and Tim13p as well as loosely associated Tim9p; its function was unclear, but it interacted structurally or functionally with the Tim9p–Tim10p complex. We now show that the two 70 kDa complexes each mediate the import of a different subset of integral inner membrane proteins and that they can transfer these proteins to one of three different membrane insertion sites: the TIM22 complex, the TIM23 complex or an as yet uncharacterized insertion site. Yeast mitochondria thus use multiple pathways for escorting hydrophobic inner membrane proteins across the aqueous intermembrane space.