Hovland R, Hesketh J E, Pryme I F
Department of Biochemistry and Molecular Biology, University of Bergen, Norway.
Int J Biochem Cell Biol. 1996 Oct;28(10):1089-105. doi: 10.1016/1357-2725(96)00059-3.
Following the synthesis of mRNA molecules in eukaryotic cells, the transcripts are processed in the nucleus and subsequently transported through the nuclear membrane into the cytoplasm before being sequestered into polysomes where the information contained in the RNA molecule is translated into an amino acid sequence. Recent evidence suggests that an association of mRNAs with the cytoskeleton might be important in targeting mechanisms and, furthermore, in the transport of mRNA from the nucleus to its correct location in the cytoplasm. Until recently, polysomes have been considered to exist in two classes, namely free or membrane-bound. There is now compelling evidence, however, that ribosomes, in addition to being associated with endoplasmic reticulum membranes, also are associated with components of the cytoskeleton. Thus, a large number of morphological and biochemical studies have shown that mRNA, polysomes and translational factors are associated with cytoskeletal structures. Although the actual nature and significance of the interaction between components of the translational apparatus and the cytoskeleton is not yet understood in detail, it would seem evident that such interactions are important in both the spatial organization and control of protein synthesis. Recent work has shown that a subcellular fraction, enriched in cytoskeletal components, contains polysomes and these (cytoskeletal-bound) polysomes have been shown to contain specific mRNA species. Thus, a population of cytoskeletal-bound polysomes may provide a specialized mechanism for the sorting, targeting and topographical segregation of mRNAs. In this review, current knowledge of the subcellular compartmentalization of mRNAs is discussed.
在真核细胞中合成mRNA分子后，转录本在细胞核中进行加工，随后通过核膜转运到细胞质中，然后被隔离到多核糖体中，在那里RNA分子中包含的信息被翻译成氨基酸序列。最近的证据表明，mRNA与细胞骨架的结合在靶向机制中可能很重要，此外，在mRNA从细胞核运输到其在细胞质中的正确位置的过程中也很重要。直到最近，多核糖体一直被认为存在两类，即游离的或与膜结合的。然而，现在有令人信服的证据表明，核糖体除了与内质网膜结合外，还与细胞骨架的成分有关。因此，大量的形态学和生化研究表明，mRNA、多核糖体和翻译因子与细胞骨架结构有关。尽管翻译装置的成分与细胞骨架之间相互作用的实际性质和意义尚未完全了解，但很明显，这种相互作用在蛋白质合成的空间组织和控制中都很重要。最近的研究表明，富含细胞骨架成分的亚细胞部分含有多核糖体，并且这些（与细胞骨架结合的）多核糖体已被证明含有特定的mRNA种类。因此，一群与细胞骨架结合的多核糖体可能为mRNA的分选、靶向和拓扑隔离提供一种特殊机制。在这篇综述中，讨论了目前关于mRNA亚细胞区室化的知识。
