Tate W P, Mansell J B, Mannering S A, Irvine J H, Major L L, Wilson D N
Department of Biochemistry and Centre for Gene Research, University of Otago, P.O. Box 56, Dunedin, New Zealand. warren.tate@stonebow. otago.ac.nz.
Biochemistry (Mosc). 1999 Dec;64(12):1342-53.
UGA remains an enigma as a signal in protein synthesis. Long recognized as a stop signal that is prone to failure when under competition from near cognate events, there was growing belief that there might be functional significance in the production of small amounts of extended proteins. This view has been reinforced with the discovery that UGA is found at some recoding sites where frameshifting occurs as a regulatory mechanism for controlling the gene expression of specific proteins, and it also serves as the code for selenocysteine (Sec), the 21st amino acid. Why does UGA among the stop signals play this role specifically, and how does it escape being used to stop protein synthesis efficiently at recoding sites involving Sec incorporation or shifts to a new translational frame? These issues concerning the UGA stop signals are discussed in this review.
在蛋白质合成中，UGA作为一种信号仍然是个谜。长期以来，UGA被认为是一个终止信号，当受到近同源事件竞争时容易失效，人们越来越相信少量延伸蛋白质的产生可能具有功能意义。随着UGA在一些重编码位点被发现，在这些位点发生移码作为控制特定蛋白质基因表达的调节机制，并且它还作为第21种氨基酸硒代半胱氨酸（Sec）的密码子，这一观点得到了加强。为什么终止信号中的UGA会特别发挥这种作用，以及它如何在涉及Sec掺入或转移到新翻译框架的重编码位点避免被有效地用于终止蛋白质合成？本综述讨论了这些关于UGA终止信号的问题。
