Caron F, Meyer E
Nature. 1985;314(6007):185-8. doi: 10.1038/314185a0.
It has long been known that messenger RNAs (mRNAs) of ciliates and in particular of Paramecium are not translated well in heterologous in vitro translation systems. Recently, we have demonstrated for Paramecium primaurelia that this phenomenon results from the presence of well-defined blocking sites in the coding sequences of almost all mRNAs, and that these sites are an intrinsic feature of the primary as opposed to the secondary structure of the mRNAs. Here we show that both the gene and the mRNA for the G surface antigen of P. primaurelia contain numerous TAA and TAG codons scattered throughout their coding sequences. We propose that these codons do not represent termination codons in P. primaurelia but instead code for glutamic acid or glutamine and that the in vitro translation of Paramecium mRNAs is blocked by their presence.
长期以来，人们一直知道纤毛虫的信使核糖核酸（mRNA），特别是草履虫的mRNA，在异源体外翻译系统中翻译效果不佳。最近，我们已经证明，对于双小核草履虫来说，这种现象是由于几乎所有mRNA的编码序列中存在明确的阻断位点，并且这些位点是mRNA一级结构而非二级结构的固有特征。在这里，我们表明双小核草履虫G表面抗原的基因和mRNA在其编码序列中都散布着大量的TAA和TAG密码子。我们提出，这些密码子在双小核草履虫中并不代表终止密码子，而是编码谷氨酸或谷氨酰胺，并且草履虫mRNA的体外翻译因其存在而受阻。
