Ray D S, Hines J C
Molecular Biology Institute, University of California, Los Angeles 90095-1570, USA.
Nucleic Acids Res. 1995 Jul 11;23(13):2526-30. doi: 10.1093/nar/23.13.2526.
Both prokaryotic and eukaryotic cells contain multiple forms of ribonuclease H, a ribonuclease that specifically degrades the RNA strand of RNA-DNA hybrids and which has been implicated in the processing of initiator RNAs and in the removal of RNA primers from Okazaki fragments. The Crithidia fasciculata RNH1 gene encodes an RNase H and was shown to be a single-copy gene in this diploid trypanosomatid. The RNH1 gene has been disrupted by targeted gene disruption using hygromycin or G418 drug-resistance cassettes. Major active forms of RNase H (38 and 45 kDa) were observed on activity gels of extracts of wild-type cells or cells in which one allele of RNH1 was disrupted. Both the 38 and 45 kDa activities were absent in extracts of cells in which both alleles of RNH1 were disrupted indicating that both forms of the C.fasciculata RNase H are encoded by the RNH1 gene.
原核细胞和真核细胞都含有多种形式的核糖核酸酶H，这是一种核糖核酸酶，它能特异性地降解RNA-DNA杂交体中的RNA链，并且与起始RNA的加工以及从冈崎片段中去除RNA引物有关。克氏锥虫的RNH1基因编码一种核糖核酸酶H，在这种二倍体锥虫中它被证明是单拷贝基因。利用潮霉素或G418耐药盒通过靶向基因破坏使RNH1基因失活。在野生型细胞或RNH1一个等位基因被破坏的细胞提取物的活性凝胶上观察到核糖核酸酶H的主要活性形式（38 kDa和45 kDa）。在RNH1两个等位基因都被破坏的细胞提取物中，38 kDa和45 kDa的活性均不存在，这表明克氏锥虫核糖核酸酶H的这两种形式均由RNH1基因编码。
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