The Tim54p-Tim22p complex mediates insertion of proteins into the mitochondrial inner membrane.
The Tim54p-Tim22p complex mediates insertion of proteins into the mitochondrial inner membrane.
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DOI：
10.1083/jcb.139.7.1663
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发表时间：
1997-12-29
期刊：
影响因子：
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通讯作者：
Jensen RE
中科院分区：
文献类型：
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作者：
Kerscher O;Holder J;Srinivasan M;Leung RS;Jensen RE
我们已经确定了一个新的蛋白质，Tim 54 p，位于酵母线粒体内膜。Tim 54 p是一个重要的输入组件，需要至少两个多位蛋白插入内膜，但不是前体易位到基质中。一些观察结果表明，Tim 54 p和Tim 22 p是内膜中的蛋白质复合物的一部分，与先前表征的Tim 23 p-Tim 17 p复合物不同。首先，TIM 22基因的多个拷贝，而不是TIM 23或TIM 17，抑制tim 54 -1温度敏感突变体的生长缺陷。第二，Tim 22 p可以与Tim 54 p从去污剂溶解的线粒体共沉淀，但Tim 54 p和Tim 22 p不与Tim 23 p或Tim 17 p相互作用。最后，tim 54 -1突变使Tim 22蛋白不稳定，但不会使Tim 23 p或Tim 17 p不稳定。我们的研究结果支持了线粒体内膜携带两个独立的输入复合物的想法：一个是跨内膜转运蛋白所需的复合物（Tim 23 p-Tim 17 p），另一个是将蛋白插入内膜所需的复合物（Tim 54 p-Tim 22 p）。
We have identified a new protein, Tim54p, located in the yeast mitochondrial inner membrane. Tim54p is an essential import component, required for the insertion of at least two polytopic proteins into the inner membrane, but not for the translocation of precursors into the matrix. Several observations suggest that Tim54p and Tim22p are part of a protein complex in the inner membrane distinct from the previously characterized Tim23p-Tim17p complex. First, multiple copies of the TIM22 gene, but not TIM23 or TIM17, suppress the growth defect of a tim54-1 temperature-sensitive mutant. Second, Tim22p can be coprecipitated with Tim54p from detergent-solubilized mitochondria, but Tim54p and Tim22p do not interact with either Tim23p or Tim17p. Finally, the tim54-1 mutation destabilizes the Tim22 protein, but not Tim23p or Tim17p. Our results support the idea that the mitochondrial inner membrane carries two independent import complexes: one required for the translocation of proteins across the inner membrane (Tim23p–Tim17p), and the other required for the insertion of proteins into the inner membrane (Tim54p–Tim22p).