DIFFERENTIAL USE OF TERMINATION CODONS IN CILIATED PROTOZOA
DIFFERENTIAL USE OF TERMINATION CODONS IN CILIATED PROTOZOA
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DOI：
10.1073/pnas.86.9.3252
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发表时间：
1989-05-01
影响因子：
11.1
通讯作者：
JAHN, CL
中科院分区：
文献类型：
--
作者：
HARPER, DS;JAHN, CL
四种纤毛虫的基因序列分析和四膜虫的tRNAs分析表明，TAG和TAA在这些生物中编码谷氨酰胺或谷氨酸，TGA是唯一的终止密码子。因此，通常认为所有的柠檬酸都使用一种非通用的遗传密码，其中TGA作为唯一的终止密码子。我们已经对纤毛虫Eplotes Crassus携带肌动蛋白基因和β-微管蛋白基因的线性DNA分子进行了测序。根据与已知的肌动蛋白和β-微管蛋白基因序列的同源性，这些基因使用TAA作为终止密码子。此外，我们还对E.crassus H4组蛋白基因3‘端的一部分进行了测序，结果表明它也使用TAA作为终止密码子。这些数据表明，纤毛虫的遗传密码改变的时间必须重新考虑。
Sequence analysis of genes in four species of ciliated protozoa and analysis of tRNAs in Tetrahymena has demonstrated that TAG ad TAA encode glutamine or glutamic acid in these organisms and TGA is the only stop codon. Thus, it has generally been assumed that all citates use a nonuniversal genetic code in which TGA acts as the sole termination codon. We have sequenced the linear DNA molecules that carry an actin gene and a .beta.-tubulin gene from the ciliate Euplotes crassus. These genes are shown to use TAA as a termination codon based on homology to known actin and .beta.-tubulin gene sequences. In addition, we have sequenced a portion of the 3'' terminus of the E. crassus H4 histone gene and show that it also uses TAA as a termination codon. These data indicate that the timing of genetic code changes in the ciliates must be reconsidered.