Institut für Physiologische Chemie, Ludwig-Maximilians Universität, München, Germany.
EMBO J. 2011 Jul 15;30(16):3232-41. doi: 10.1038/emboj.2011.235.
The TOM complex of the outer membrane of mitochondria is the entry gate for the vast majority of precursor proteins that are imported into the mitochondria. It is made up by receptors and a protein conducting channel. Although precursor proteins of all subcompartments of mitochondria use the TOM complex, it is not known whether its channel can only mediate passage across the outer membrane or also lateral release into the outer membrane. To study this, we have generated fusion proteins of GFP and Tim23 which are inserted into the inner membrane and, at the same time, are spanning either the TOM complex or are integrated into the outer membrane. Our results demonstrate that the TOM complex, depending on sequence determinants in the precursors, can act both as a protein conducting pore and as an insertase mediating lateral release into the outer membrane.
线粒体的外膜 TOM 复合物是绝大多数进入线粒体的前体蛋白的入口。它由受体和蛋白质传导通道组成。尽管线粒体的所有亚区室的前体蛋白都使用 TOM 复合物，但尚不清楚其通道是否只能介导穿过外膜，还是也能进行横向释放到外膜中。为了研究这一点，我们生成了 GFP 和 Tim23 的融合蛋白，它们插入到内膜中，同时跨越 TOM 复合物或整合到外膜中。我们的结果表明，TOM 复合物可以根据前体蛋白中的序列决定因素，既作为蛋白质传导孔，又作为介导横向释放到外膜的插入酶。
