Tuite M F, Stansfield I
Research School of Biosciences, University of Kent, Canterbury, UK.
Mol Biol Rep. 1994 May;19(3):171-81. doi: 10.1007/BF00986959.
One of three mRNA codons--UAA, UAG and UGA--is used to signal to the elongating ribosome that translation should be terminated at this point. Upon the arrival of the stop codon at the ribosomal acceptor(A)-site, a protein release factor (RF) binds to the ribosome resulting in the peptidyl transferase centre of the ribosome switching to a hydrolytic function to remove the completed polypeptide chain from the peptidyl-tRNA bound at the adjacent ribosomal peptidyl(P)-site. In this review recent advances in our understanding of the mechanism of termination in the bacterium Escherichia coli will be summarised, paying particular attention to the roles of 16S ribosomal RNA and the release factors RF-1, RF-2 and RF-3 in stop codon recognition. Our understanding of the translation termination process in eukaryotes is much more rudimentary with the identity of the single eukaryotic release factor (eRF) still remaining elusive. Finally, several examples of how the termination mechanism can be subverted either to expand the genetic code (e.g. selenocysteine insertion at UGA codons) or to regulate the expression of mammalian retroviral or plant viral genomes will be discussed.
三种mRNA密码子（UAA、UAG和UGA）中的一种用于向正在延伸的核糖体发出信号，表明翻译应在此处终止。当终止密码子到达核糖体的受体（A）位点时，一种蛋白质释放因子（RF）会与核糖体结合，导致核糖体的肽基转移酶中心转变为水解功能，从而将完整的多肽链从结合在相邻核糖体肽基（P）位点的肽基-tRNA上移除。在这篇综述中，我们将总结对细菌大肠杆菌中终止机制理解的最新进展，特别关注16S核糖体RNA以及释放因子RF-1、RF-2和RF-3在终止密码子识别中的作用。我们对真核生物翻译终止过程的理解还非常初步，单一真核生物释放因子（eRF）的身份仍然难以捉摸。最后，将讨论几个终止机制被颠覆的例子，这些例子要么是为了扩展遗传密码（例如在UGA密码子处插入硒代半胱氨酸），要么是为了调控哺乳动物逆转录病毒或植物病毒基因组的表达。
