Department of Biology, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
Proc Natl Acad Sci U S A. 1986 Jul;83(14):5160-4. doi: 10.1073/pnas.83.14.5160.
The macronucleus of Tetrahymena thermophila contains a single actin gene. We have isolated this gene from a partial plasmid library by using the yeast actin gene as a probe. The nucleotide sequence of the gene has been determined and the amino acid sequence of the potential protein deduced. The encoded protein is 375 amino acids long, one amino acid longer than the yeast actin. It is one of the most divergent actins sequenced to date, being only 75% homologous to yeast actin. Unlike the actin genes from most other organisms, it does not contain introns. The coding region contains TAA and TAG codons; the translation termination codon is TGA. Comparison of the amino acid sequence of the Tetrahymena actin with that of actins from other organisms suggests that TAG may code for glutamic acid. The gene is transcribed from multiple initiation sites between 57 and 98 nucleotides upstream of the translation start codon. The 5' flanking region is very A+T-rich and contains numerous "TATA-like" sequences upstream of the transcription start sites.
嗜热四膜虫的巨核含有一个单一的肌动蛋白基因。我们使用酵母肌动蛋白基因作为探针，从一个部分质粒文库中分离出这个基因。该基因的核苷酸序列已被确定，潜在蛋白质的氨基酸序列也已推导出来。编码的蛋白质长 375 个氨基酸，比酵母肌动蛋白长一个氨基酸。它是迄今为止测序的最具差异的肌动蛋白之一，与酵母肌动蛋白的同源性仅为 75%。与大多数其他生物体的肌动蛋白基因不同，它不包含内含子。编码区包含 TAA 和 TAG 密码子；翻译终止密码子是 TGA。嗜热四膜虫肌动蛋白的氨基酸序列与其他生物体的肌动蛋白的比较表明，TAG 可能编码谷氨酸。该基因从翻译起始密码子上游 57 到 98 个核苷酸处的多个起始位点转录。5'侧翼区富含 A+T，在转录起始位点上游有许多“TATA 样”序列。
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