人类DNA拓扑异构酶I基因3'区特征。
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周斌，Bastow KF，程永昌
人类DNA拓扑异构酶I基因3'区特征。
癌症决议1989年7月15日;49(14):3922-7。
- PubMed ID
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2544263 (PubMed视图］
- 摘要
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前人研究表明拓扑异构酶I (Topo I)在细胞生长中起着至关重要的作用。然而，Topo I基因的结构尚未确定。从HeLa和KB细胞cDNA文库中分别分离到两个人Topo I 4.1千碱基mRNA互补DNA (cDNA)克隆。这些克隆全部相同，包含679个编码碱基对和1138个非编码碱基对。与人胎盘的Topo I cDNA相比，该克隆在3'非编码区有两个碱基的差异。从6个人类肿瘤细胞系中检测了人Topo I基因3'端结构。Topo I cDNA分别识别了16.5、24.2和16.0个碱基的基因组DNA，这些碱基分别被EcoRI、indiii和PstI限制。通过双酶切和cDNA亚克隆杂交对单个基因组片段进行排序。cDNA亚克隆的消化和杂交。结果表明，人Topo I基因中存在多个介入序列。 The gene arrangement was similar in all six cell lines and no polymorphism was observed. However, each digestion contained genomic fragments that hybridized with all the subclones, suggesting that at least one Topo I pseudogene, or another Topo I gene with a different structure, was present in every cell line. As predicted, double digestions generated at 161 base pair fragment that indicates the presence of an intronless pseudogene. In contrast to the DNA topoisomerase I gene, the presumptive pseudogene(s) appears to be hypomethylated. In addition to the 4.1-kilobase Topo I mRNA, a larger 6-kilobase RNA was identified in human KB and HeLa cells which could be a processed Topo I mRNA intermediate.