Horowitz S, Gorovsky M A
Proc Natl Acad Sci U S A. 1985 Apr;82(8):2452-5. doi: 10.1073/pnas.82.8.2452.
We have cloned and partially sequenced two histone H3 genes of Tetrahymena thermophila. The DNA sequences strongly suggest that both genes are active in the vegetatively growing cell. Comparison of the derived amino acid sequences of these two genes with the actual sequence of Tetrahymena histone H3 results in the surprising conclusion that TAA codes for glutamine. This represents the first demonstration of a coding function for this termination codon of the "universal" code. This observation has important implications for the evolution of ciliates and of the genetic code.
我们已经克隆了嗜热四膜虫的两个组蛋白H3基因并进行了部分测序。DNA序列强烈表明这两个基因在营养生长细胞中都是活跃的。将这两个基因推导的氨基酸序列与嗜热四膜虫组蛋白H3的实际序列进行比较,得出了一个惊人的结论,即TAA编码谷氨酰胺。这是对“通用”密码中这个终止密码子编码功能的首次证明。这一观察结果对纤毛虫和遗传密码的进化具有重要意义。