Mitochondrial presequence translocase: Switching between TOM tethering and motor recruitment involves Tim21 and Tim17
Mitochondrial presequence translocase: Switching between TOM tethering and motor recruitment involves Tim21 and Tim17
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DOI：
10.1016/j.cell.2005.01.011
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发表时间：
2005-03-25
期刊：
影响因子：
64.5
通讯作者：
Rehling, P
中科院分区：
文献类型：
--
作者：
Chacinska, A;Lind, M;Rehling, P
线粒体内膜的前序列易位酶（TIM 23复合物）在蛋白质输入的中心连接处起作用。它接受来自外膜TOM复合物的前蛋白，并将它们引导到内膜插入，或者与前序列易位酶相关马达（PAM）合作，引导到基质。关于TIM 23复合体如何协调这些任务，我们知之甚少。我们已经鉴定了与TOM复合物相互作用的Tim 21（YGR 033 c）。Tim 21特异于与TOM合作并促进内膜插入的TIM 23形式。蛋白质易位到基质中需要切换到无Tim 21的PAM结合的前序列易位酶。Tim 17通过执行两个可分离的功能对开关至关重要：促进内膜插入和结合Pam 18以形成功能性TIM-PAM复合物。因此，前序列易位酶不是静态复合物，而是在涉及Tim 21和Tim 17的反应循环中在TOM系链和PAM结合之间切换。
The presequence translocase of the inner mitochondrial membrane (TIM23 complex) operates at a central junction of protein import. It accepts preproteins from the outer membrane TOM complex and directs them to inner membrane insertion or, in cooperation with the presequence translocase-associated motor (PAM), to the matrix. Little is known of how the TIM23 complex coordinates these tasks. We have identified Tim21 (YGR033c) that interacts with the TOM complex. Tim21 is specific for a TIM23 form that cooperates with TOM and promotes inner membrane insertion. Protein translocation into the matrix requires a switch to a Tim21-free, PAM bound presequence translocase. Tim17 is crucial for the switch by performing two separable functions: promotion of inner membrane insertion and binding of Pam18 to form the functional TIM-PAM complex. Thus, the presequence translocase is not a static complex but switches between TOM tethering and PAM binding in a reaction cycle involving Tim21 and Tim17.