Tom5 functionally links mitochondrial preprotein receptors to the general import pore
Tom5 functionally links mitochondrial preprotein receptors to the general import pore
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DOI：
10.1038/40663
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发表时间：
1997-07-10
期刊：
影响因子：
64.8
通讯作者：
Pfanner, N
中科院分区：
文献类型：
--
作者：
Dietmeier, K;Honlinger, A;Pfanner, N
大多数线粒体蛋白质在胞质多聚核糖体上作为前蛋白合成，随后输入细胞器（1-3）。线粒体外膜含有多亚基前蛋白转位酶（Tom），其在胞质侧具有受体，并且在膜中具有一般输入孔（GIP）。Tom 20-Tom 22和Tom 70-Tom 37作为输入受体（4-7）起作用，分别偏好具有氨基末端前序列或内部靶向信息的前蛋白。Tom 40是GIP的重要组成部分（8，9），而Tom 6和Tom 7调节Tom机制的组装和解离（10，11）。在这里，我们报告的识别Tom 5，一个小的亚基，有一个至关重要的作用进口注定为所有四个线粒体亚室的前蛋白。Tom 5具有单个膜锚和带负净电荷的胞质片段，并接受来自受体的前蛋白并介导它们插入GIP。我们得出结论，Tom 5代表了表面受体和GIP之间的功能联系，并且是引导带正电荷的线粒体靶向序列逐步转运的“酸链”的一部分（5）。
Most mitochondrial proteins are synthesized as preproteins on cytosolic polysomes and are subsequently imported into the organelle(1-3). The mitochondrial outer membrane contains a multisubunit preprotein translocase (Tom) which has receptors on the cytosolic side and a general import pore (GIP) in the membrane. Tom20-Tom22 and Tom70-Tom37 function as import receptors(4-7) with a preference for preproteins that have amino-terminal presequences or internal targeting information, respectively. Tom40 is an essential constituent of the GIP(8,9), whereas Tom6 and Tom7 modulate the assembly and dissociation of the Tom machinery(10,11). Here we report the identification of Tom5, a small subunit that has a crucial role importing preproteins destined for all four mitochondrial subcompartments. Tom5 has a single membrane anchor and a cytosolic segment with a negative net charge, and accepts preproteins from the receptors and mediates their insertion into the GIP. We conclude that Tom5 represents a functional link between surface receptors and GIP, and is part of an 'acid chain'(5) that guides the stepwise transport of positively charged mitochondrial targeting sequences.