Helftenbein E
Nucleic Acids Res. 1985 Jan 25;13(2):415-33. doi: 10.1093/nar/13.2.415.
The gene-sized macronuclear DNA of the hypotrichous ciliate Stylonychia lemnae contains two size classes of DNA molecules (1.85 and 1.73 kbp) coding for alpha-tubulin. Each macronucleus contains about 55000 copies of the 1.85 kbp molecules and about 17000 copies of the 1.73 kbp DNA molecules. Five macronuclear molecules of these sequences were cloned and sequenced, one, from the 1.85 kbp size class in its entirety. The 5 sequences fell into two classes suggesting that Stylonychia lemnae contains at least two different alpha-tubulin genes. All 5 clones show the codon TAA in the same nucleotide positions of the coding region. In this position the TAA codon cannot function as a translational stop codon and we suggest that this codon codes for the amino acid glutamine. The nucleotide sequence of the coding region as well as the encoded amino acid sequence is highly conserved compared to alpha-tubulin genes from vertebrates. The noncoding regions show several putative transcription-regulatory sequences as well as sequences presumably functioning as replication origins.
纤毛类低等真核生物莱氏拟尾柱虫的基因大小的大核DNA含有两类编码α-微管蛋白的DNA分子（1.85和1.73千碱基对）。每个大核含有约55000个1.85千碱基对分子的拷贝和约17000个1.73千碱基对DNA分子的拷贝。克隆并测序了这些序列的五个大核分子，其中一个是完整的1.85千碱基对大小类别的分子。这5个序列分为两类，表明莱氏拟尾柱虫至少含有两个不同的α-微管蛋白基因。所有5个克隆在编码区的相同核苷酸位置都显示密码子TAA。在这个位置，TAA密码子不能作为翻译终止密码子起作用，我们认为这个密码子编码氨基酸谷氨酰胺。与脊椎动物的α-微管蛋白基因相比，编码区的核苷酸序列以及编码的氨基酸序列高度保守。非编码区显示出几个推定的转录调控序列以及可能作为复制起点起作用的序列。
