Andreasen P H, Dreisig H, Kristiansen K
Department of Molecular Biology, Odense University, Denmark.
Biochem J. 1987 Jun 1;244(2):331-5. doi: 10.1042/bj2440331.
The codon usage of Tetrahymena thermophila and other ciliates deviates from the 'universal genetic code' in that UAA and probably UAG are not translational termination signals but code for glutamine. Therefore, translation in vitro of mRNA from Tetrahymena in a reticulocyte lysate is prematurely terminated if a UAA or UAG triplet is present in the reading frame of the mRNA. We show that the addition of a subcellular fraction from Tetrahymena thermophila enables a rabbit reticulocyte lysate to translate Tetrahymena mRNAs into full-sized proteins. The activity of the subcellular fraction is shown to depend on the combined function of a protein component(s) and a tRNA(s). The subcellular fraction is easily prepared and its usefulness for the identification of isolated mRNAs from Tetrahymena by their translation products in vitro is demonstrated.
嗜热四膜虫和其他纤毛虫的密码子使用情况与“通用遗传密码”不同，因为UAA以及可能的UAG并非翻译终止信号，而是编码谷氨酰胺。因此，如果mRNA的阅读框中存在UAA或UAG三联体，嗜热四膜虫mRNA在网织红细胞裂解物中的体外翻译会过早终止。我们发现，添加嗜热四膜虫的亚细胞组分能使兔网织红细胞裂解物将嗜热四膜虫mRNA翻译成全长蛋白质。结果表明，该亚细胞组分的活性取决于一种或多种蛋白质成分与一种或多种tRNA的联合功能。这种亚细胞组分易于制备，并且通过体外翻译产物证明了其对于鉴定从嗜热四膜虫分离的mRNA的有用性。
