Department of Chemistry, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, Aichi-ken, Japan.
EMBO Rep. 2010 Mar;11(3):187-93. doi: 10.1038/embor.2009.283. Epub 2010 Jan 29.
The mitochondrial outer membrane contains two protein translocators: the TOM40 and TOB/SAM complexes. Mdm10 is distributed in the TOB complex for beta-barrel protein assembly and in the MMM1 complex for tethering of the endoplasmic reticulum and mitochondria. Here, we establish a system in which the Mdm10 level in the TOB complex--but not in the MMM1 complex--is altered to analyse its part in beta-barrel protein assembly. A decrease in the Mdm10 level results in accumulation of in vitro imported Tom40, which is a beta-barrel protein, at the level of the TOB complex. An increase in the Mdm10 level inhibits association not only of Tom40 but also of other beta-barrel proteins with the TOB complex. These results show that Mdm10 regulates the timing of release of unassembled Tom40 from the TOB complex, to facilitate its coordinated assembly into the TOM40 complex.
TOM40 和 TOB/SAM 复合物。Mdm10 分布在 TOB 复合物中，用于 β-桶状蛋白的组装，以及在 MMM1 复合物中，用于内质网和线粒体的连接。在这里，我们建立了一个系统，改变 TOB 复合物中 Mdm10 的水平，而不改变 MMM1 复合物中 Mdm10 的水平，以分析其在 β-桶状蛋白组装中的作用。Mdm10 水平的降低会导致体外导入的 Tom40（一种 β-桶状蛋白）在 TOB 复合物水平上的积累。Mdm10 水平的升高不仅抑制了 Tom40 的结合，也抑制了其他 β-桶状蛋白与 TOB 复合物的结合。这些结果表明，Mdm10 调节了未组装的 Tom40 从 TOB 复合物中释放的时机，以促进其协调组装到 TOM40 复合物中。
