Detection in HeLa cell extracts of a 7-methyl guanosine specific enzyme activity that cleaves m7GpppNm

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摘要：

Extracts prepared from HeLa cells contain an enzymatic activity which cleaves m 7G(5′)ppp(5′)G m to m 7pG and ppG m. The activity exhibits a high degree of substrate specificity and does not cleave G(5′)ppp(5′)G or the ring opened derivative of m 7GpppG m which has lost the positive charge from the N 7 position of m 7G. m 7GpppG m as the 5′ terminal structure of intact reovirus mRNA is resistant to attack by the pyrophosphatase activity, but becomes partially sensitive in the 5′ terminal fragment consisting of 7–10 nucleotides derived from the same mRNA by T1 RNAase digestion. m 7G(5′)ppp(5′)G mpCp is completely sensitive to cleavage resulting in the release of m 7pG without generation of m 7GpppG m as an intermediate. These results establish the existence of a 7-methyl guanosine specific pyrophosphatase activity in HeLa cells.

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关键词：

Humans Coliphages DNA Viruses Hela Cells Reoviridae Pyrophosphatases Ribonucleases Guanine Nucleotides RNA, Viral Guanosine