Cyr D M
Department of Cell Biology, School of Medicine, University of Alabama at Birmingham 35294-0005, USA.
J Bioenerg Biomembr. 1997 Feb;29(1):29-34. doi: 10.1023/a:1022455621111.
A dynamic complex between the mitochondrial cognate of hsp70 (mthsp70) and the inner membrane protein tim44 couples energy derived from ATP hydrolysis to drive multiple steps in the mitochondrial protein import pathway: (1) The delta psi dependent import step and the mthsp70/tim44 complex cooperate to facilitate the unidirectional transfer of the mitochondrial targeting signal across the inner membrane. (2) The mthsp70/tim44 complex helps to unfold domains on precursors proteins that arrive at the import apparatus in a folded conformation on the cis side of the outer membrane. (3) Completion of import is then driven by the mthsp70/ tim44 complex in a manner that is independent of delta psi. Mechanisms proposed to explain how the mthsp70/tim44 complex harvests chemical energy to drive these aspects of the import process are discussed.
热休克蛋白70（hsp70）的线粒体同源物（mthsp70）与内膜蛋白tim44之间形成的动态复合体，将ATP水解产生的能量耦合起来，以驱动线粒体蛋白质导入途径中的多个步骤：（1）依赖于膜电位差（delta psi）的导入步骤与mthsp70/tim44复合体协同作用，促进线粒体靶向信号单向穿过内膜。（2）mthsp70/tim44复合体有助于展开以外膜顺式侧折叠构象到达导入装置的前体蛋白上的结构域。（3）然后，导入的完成由mthsp70/tim44复合体以独立于膜电位差的方式驱动。本文讨论了为解释mthsp70/tim44复合体如何获取化学能量以驱动导入过程这些方面而提出的机制。
