Weis Benjamin L, Schleiff Enrico, Zerges William
Goether University, Cluster of Excellence Macromolecular Complexes, Institute for Molecular Biosciences, Max-von-Laue Str. 9, D-60438 Frankfort, Germany.
Biochim Biophys Acta. 2013 Feb;1833(2):260-73. doi: 10.1016/j.bbamcr.2012.04.004.
Cells have complex membranous organelles for the compartmentalization and the regulation of most intracellular processes. Organelle biogenesis and maintenance requires newly synthesized proteins, each of which needs to go from the ribosome translating its mRNA to the correct membrane for insertion or transclocation to an a organellar subcompartment. Decades of research have revealed how proteins are targeted to the correct organelle and translocated across one or more organelle membranes ro the compartment where they function. The paradigm examples involve interactions between a peptide sequence in the protein, localization factors, and various membrane embedded translocation machineries. Membrane translocation is either cotranslational or posttranslational depending on the protein and target organelle. Meanwhile research in embryos, neurons and yeast revealed an alternative targeting mechanism in which the mRNA is localized and only then translated to synthesize the protein in the correct location. In these cases, the targeting information is coded by the cis-acting sequences in the mRNA ("Zipcodes") that interact with localization factors and, in many cases, are transported by the molecular motors on the cytoskeletal filaments. Recently, evidence has been found for this "mRNA based" mechanism in organelle protein targeting to endoplasmic reticulum, mitochondria, and the photosynthetic membranes within chloroplasts. Here we review known and potential roles of mRNA localization in protein targeting to and within organelles. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.
细胞具有复杂的膜性细胞器，用于大多数细胞内过程的区室化和调节。细胞器的生物发生和维持需要新合成的蛋白质，其中每一种蛋白质都需要从翻译其mRNA的核糖体到达正确的膜，以便插入或转运到细胞器亚区室。数十年的研究揭示了蛋白质如何被靶向到正确的细胞器，并穿过一层或多层细胞器膜转运到它们发挥功能的区室。典型的例子涉及蛋白质中的肽序列、定位因子和各种膜嵌入转运机制之间的相互作用。根据蛋白质和靶细胞器的不同，膜转运可以是共翻译的，也可以是翻译后进行的。与此同时，对胚胎、神经元和酵母的研究揭示了一种替代的靶向机制，即mRNA先定位，然后才在正确的位置进行翻译以合成蛋白质。在这些情况下，靶向信息由mRNA中的顺式作用序列（“邮政编码”）编码，这些序列与定位因子相互作用，并且在许多情况下，由细胞骨架丝上的分子马达运输。最近，在细胞器蛋白靶向内质网、线粒体和叶绿体中的光合膜的过程中，已经发现了这种“基于mRNA”机制的证据。在这里，我们综述了mRNA定位在蛋白质靶向细胞器及细胞器内的已知和潜在作用。本文是名为“线粒体和质体中的蛋白质导入与质量控制”的特刊的一部分。
