Differences in the Methylation of Transfer Ribonucleic Acid in VVitro by the Mitochondrial and Cytoplasmic Transfer Ribonucleic Acid Methylases of HeLa Cells
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چکیده
The methylation of Escherichia coli B transfer RNA in vitro by HeLa mitochondrial and cytoplasmic extracts was examined. The following differences were found. (a) The cytoplasmic extract methylated E. coli B tRNA to a much greater extent than did the mitochondrial extract. (b) The two extracts methylated different sites on E. coli B tRNA, thereby generating different methylated oligonucleotide sequences. (c) The methylated base composition of E. coli B tRNA methylated in vitro indicated that 2-methyladenine tRNA methylase activity was uniquely associated with the mitochondria, while iWdimethylguanine tRNA methylase activity was uniquely associated with the cytoplasm. The presence of 2-methyladenine tRNA methylase activity in HeLa mitochondria and its absence in HeLa cytoplasm was taken as evidence for the existence of at least one mitochondrial-specific methylase. In addition, since Z-methyladenine is commonly found in prokaryote tRNA but not in eukaryote cytoplasmic tRNA, it was suggested that the presence of 2-methyladenine tRNA methylase activity in mitochondria was evidence that mitochondria might have evolved from prokaryote cells.
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Differences in the Methylation of Transfer Ribonucleic Acid in VVitro by the Mitochondrial and Cytoplasmic Transfer Ribonucleic Acid Methylases of HeLa Cells
The methylation of Escherichia coli B transfer RNA in vitro by HeLa mitochondrial and cytoplasmic extracts was examined. The following differences were found. (a) The cytoplasmic extract methylated E. coli B tRNA to a much greater extent than did the mitochondrial extract. (b) The two extracts methylated different sites on E. coli B tRNA, thereby generating different methylated oligonucleotide ...
متن کاملDifferences in the methylation of transfer ribonucleic acid in vitro by the mitochondrial and cytoplasmic transfer ribonucleic acid methylases of HeLa cells.
The methylation of Escherichia coli B transfer RNA in vitro by HeLa mitochondrial and cytoplasmic extracts was examined. The following differences were found. (a) The cytoplasmic extract methylated E. coli B tRNA to a much greater extent than did the mitochondrial extract. (b) The two extracts methylated different sites on E. coli B tRNA, thereby generating different methylated oligonucleotide ...
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