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- Shiota, Takuya, et al.
(author)
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Molecular architecture of the active mitochondrial protein gate
- 2015
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 349:6255, s. 1544-1548
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Journal article (peer-reviewed)abstract
- Mitochondria fulfill central functions in cellular energetics, metabolism, and signaling. The outer membrane translocator complex (the TOM complex) imports most mitochondrial proteins, but its architecture is unknown. Using a cross-linking approach, we mapped the active translocator down to single amino acid residues, revealing different transport paths for preproteins through the Tom40 channel. An N-terminal segment of Tom40 passes from the cytosol through the channel to recruit chaperones fromthe intermembrane space that guide the transfer of hydrophobic preproteins. The translocator contains three Tom40 beta-barrel channels sandwiched between a central alpha-helical Tom22 receptor cluster and external regulatory Tom proteins. The preprotein-translocating trimeric complex exchanges with a dimeric isoform to assemble new TOM complexes. Dynamic coupling of alpha-helical receptors, beta-barrel channels, and chaperones generates a versatile machinery that transports about 1000 different proteins.
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- van der Laan, Martin, et al.
(author)
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Motor-free mitochondrial presequence translocase drives membrane integration of preproteins
- 2007
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In: Nature Cell Biology. - : Springer Science and Business Media LLC. - 1465-7392 .- 1476-4679. ; 9:10, s. 1152-1159
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Journal article (peer-reviewed)abstract
- The mitochondrial inner membrane is the central energy-converting membrane of eukaryotic cells. the electrochemical proton gradient generated by the respiratory chain drives the ATP synthase. to maintain this proton-motive force, the inner membrane forms a tight barrier and strictly controls the translocation of ions(1). However, the major preprotein transport machinery of the inner membrane, termed the presequence translocase, translocates polypeptide chains into or across the membrane(2-9). Different views exist of the molecular mechanism of the translocase, in particular of the coupling with the import motor of the matrix(8,10,11). Wehave reconstituted preprotein transport into the mitochondrial inner membrane by incorporating the purified presequence translocase into cardiolipin-containing liposomes. We show that the motor-free form of the presequence translocase integrates preproteins into the membrane. the reconstituted presequence translocase responds to targeting peptides and mediates voltage-driven preprotein translocation, lateral release and insertion into the lipid phase. thus, the minimal system for preprotein integration into the mitochondrial inner membrane is the presequence translocase, a cardiolipin-rich membrane and a membrane potential.
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