Koehler C M, Merchant S, Oppliger W, Schmid K, Jarosch E, Dolfini L, Junne T, Schatz G, Tokatlidis K
Biochemie, Biozentrum der Universität Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
EMBO J. 1998 Nov 16;17(22):6477-86. doi: 10.1093/emboj/17.22.6477.
Tim10p, a protein of the yeast mitochondrial intermembrane space, was shown previously to be essential for the import of multispanning carrier proteins from the cytoplasm into the inner membrane. We now identify Tim9p, another essential component of this import pathway. Most of Tim9p is associated with Tim10p in a soluble 70 kDa complex. Tim9p and Tim10p co-purify in successive chromatographic fractionations and co-immunoprecipitated with each other. Tim9p can be cross-linked to a partly translocated carrier protein. A small fraction of Tim9p is bound to the outer face of the inner membrane in a 300 kDa complex whose other subunits include Tim54p, Tim22p, Tim12p and Tim10p. The sequence of Tim9p is 25% identical to that of Tim10p and Tim12p. A Ser67-->Cys67 mutation in Tim9p suppresses the temperature-sensitive growth defect of tim10-1 and tim12-1 mutants. Tim9p is a new subunit of the TIM machinery that guides hydrophobic inner membrane proteins across the aqueous intermembrane space.
Tim10p是酵母线粒体膜间隙的一种蛋白质，先前已证明它对于多跨膜载体蛋白从细胞质转运到内膜至关重要。我们现在鉴定出Tim9p，它是该转运途径的另一个必需组分。Tim9p的大部分与Tim10p结合形成一个可溶性的70 kDa复合物。Tim9p和Tim10p在连续的色谱分级分离中共同纯化，并相互进行共免疫沉淀。Tim9p可以与部分转运的载体蛋白交联。一小部分Tim9p以一个300 kDa复合物的形式结合在内膜的外表面，该复合物的其他亚基包括Tim54p、Tim22p、Tim12p和Tim10p。Tim9p的序列与Tim10p和Tim12p的序列有25%的同源性。Tim9p中的Ser67→Cys67突变可抑制tim10 - 1和tim12 - 1突变体的温度敏感型生长缺陷。Tim9p是TIM机制的一个新亚基，可引导疏水性内膜蛋白穿过水相的膜间隙。
