Research Group Membrane Biogenesis, University of Kaiserslautern, Kaiserslautern, Germany.
Bioessays. 2010 Dec;32(12):1050-7. doi: 10.1002/bies.201000081. Epub 2010 Oct 21.
The ribosomal polypeptide tunnel exit is the site where a variety of factors interact with newly synthesized proteins to guide them through the early steps of their biogenesis. In mitochondrial ribosomes, this site has been considerably modified in the course of evolution. In contrast to all other translation systems, mitochondrial ribosomes are responsible for the synthesis of only a few hydrophobic membrane proteins that are essential subunits of the mitochondrial respiratory chain. Membrane insertion of these proteins occurs co-translationally and is connected to a sophisticated assembly process that not only includes the assembly of the different subunits but also the acquisition of redox co-factors. Here, we describe how mitochondrial translation is organized in the context of respiratory chain assembly and speculate how alteration of the ribosomal tunnel exit might allow the establishment of a subset of specialized ribosomes that individually organize the early steps in the biogenesis of distinct mitochondrially-encoded proteins.
核糖体多肽出口是各种因素与新合成蛋白质相互作用的场所，引导它们完成生物发生的早期步骤。在线粒体核糖体中，这个位点在进化过程中发生了很大的改变。与所有其他翻译系统不同，线粒体核糖体只负责合成少数几种疏水性膜蛋白，这些蛋白是线粒体呼吸链的必需亚基。这些蛋白质的膜插入是共翻译发生的，并与一个复杂的组装过程相关联，该过程不仅包括不同亚基的组装，还包括氧化还原辅助因子的获取。在这里，我们描述了线粒体翻译在呼吸链组装背景下是如何组织的，并推测核糖体隧道出口的改变如何允许建立一组专门的核糖体，这些核糖体可以单独组织不同线粒体编码蛋白生物发生的早期步骤。
