Leuenberger D, Bally N A, Schatz G, Koehler C M
Biozentrum der Universität Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
EMBO J. 1999 Sep 1;18(17):4816-22. doi: 10.1093/emboj/18.17.4816.
Earlier work on the protein import system of yeast mitochondria has identified two soluble 70 kDa protein complexes in the intermembrane space. One complex contains the essential proteins Tim9p and Tim10p and mediates transport of cytosolically-made metabolite carrier proteins from the outer to the inner membrane. The other complex contains the non-essential proteins Tim8p and Tim13p as well as loosely associated Tim9p; its function was unclear, but it interacted structurally or functionally with the Tim9p-Tim10p complex. We now show that the two 70 kDa complexes each mediate the import of a different subset of integral inner membrane proteins and that they can transfer these proteins to one of three different membrane insertion sites: the TIM22 complex, the TIM23 complex or an as yet uncharacterized insertion site. Yeast mitochondria thus use multiple pathways for escorting hydrophobic inner membrane proteins across the aqueous intermembrane space.
早期对酵母线粒体蛋白质导入系统的研究，已在膜间隙中鉴定出两种可溶性70 kDa蛋白质复合物。一种复合物包含必需蛋白Tim9p和Tim10p，并介导细胞质中合成的代谢物载体蛋白从外膜向内膜的转运。另一种复合物包含非必需蛋白Tim8p和Tim13p以及松散结合的Tim9p；其功能尚不清楚，但在结构或功能上与Tim9p - Tim10p复合物相互作用。我们现在表明，这两种70 kDa复合物各自介导不同子集的线粒体内膜整合蛋白的导入，并且它们可以将这些蛋白质转移到三个不同的膜插入位点之一：TIM22复合物、TIM23复合物或一个尚未表征的插入位点。因此，酵母线粒体利用多种途径护送疏水的内膜蛋白穿过水相的膜间隙。
