Abstract
In eukaryotic DNA, 50-90% of the dinucleotide sequence C-G is methylated. Most methylated sites are apparently placed at fixed locations in the genome and this methylation pattern is faithfully inherited from generation to generation1. Holliday and Pugh2 and Riggs3 have suggested that methyl moieties are inherited in a semi-conservative fashion during DNA replication, and this model has been confirmed by experiments in which methylated DNA was integrated into mouse L-cells following DNA-mediated gene transfer4-6. For this mechanism to operate, two basic requirements must be satisfied: (1) methyl moieties must be symmetrically placed on both strands of the DNA7,8 and (2) the cellular methylase should be specific for the hemi-methylated substrate present during DNA replication. Here we demonstrate conclusively that the preferred substrate in vitro for the mouse ascites DNA methylase is indeed hemi-methylated DNA. Furthermore, this enzyme seems to methylate exclusively cytosine residues located at the dinucleotide C-G.
Original language | English |
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Pages (from-to) | 620-622 |
Number of pages | 3 |
Journal | Nature |
Volume | 295 |
Issue number | 5850 |
DOIs | |
State | Published - 1982 |