Winkler M M, Bruening G, Hershey J W
Eur J Biochem. 1983 Dec 1;137(1-2):227-32. doi: 10.1111/j.1432-1033.1983.tb07819.x.
Translation of a variety of RNAs was studied in a cell-free translation system derived from sea urchin eggs. While RNAs such as globin or tobacco mosaic virus are efficiently translated, viral RNAs which do not contain the 5' cap structure, such as cow pea mosaic virus (CPMV) and poliovirus, are not translated. Mixing experiments with reticulocyte lysates indicated that the lack of translation of uncapped viral RNAs is not due to the presence of a potent inhibitor or the absence of an activating agent. RNA competition experiments between capped and uncapped RNAs indicated that uncapped RNAs do not interact with the sea urchin egg initiation machinery. Proteolytic removal of the 5' viral protein did not allow the translation of CPMV RNA. However, chemical decapping of vesicular stomatitis virus mRNA completely inhibited the translation of this mRNA in the sea urchin cell-free system. We conclude that the sea urchin egg lacks the initiation pathway used to initiate uncapped mRNAs in mammalian cells and thus has an absolute requirement for the 5' cap structure for initiation. In addition we discuss the implications of these findings for the control of protein synthesis after fertilization of the sea urchin egg.
在源自海胆卵的无细胞翻译系统中研究了多种RNA的翻译情况。虽然诸如珠蛋白或烟草花叶病毒等RNA能够高效翻译，但不含5'帽结构的病毒RNA，如豇豆花叶病毒（CPMV）和脊髓灰质炎病毒，则不能被翻译。用网织红细胞裂解物进行的混合实验表明，无帽病毒RNA不能翻译并非是由于存在强效抑制剂或缺乏激活剂。有帽和无帽RNA之间的RNA竞争实验表明，无帽RNA不与海胆卵起始机制相互作用。用蛋白酶去除病毒的5'蛋白并不能使CPMV RNA进行翻译。然而，水泡性口炎病毒mRNA的化学脱帽完全抑制了其在海胆无细胞系统中的翻译。我们得出结论，海胆卵缺乏用于起始哺乳动物细胞中无帽mRNA的起始途径，因此对于起始过程绝对需要5'帽结构。此外，我们讨论了这些发现对海胆卵受精后蛋白质合成控制的影响。
