Coupled Demethylation of Sites in a Conserved Sequence of Xenopus Ribosomal DNA
- A. La Volpe,
- M. Taggart,
- D. Macleod, and
- A. Bird
This extract was created in the absence of an abstract.
Excerpt
Like many cellular macromolecules, DNA is subject to postsynthetic modification. In animals, the most common modification involves methylation of cytosine in the dinucleotide sequence CpG (Wyatt 1951; Doscocil and Sorm 1962; Grippo et al. 1968; Vanyushin et al. 1970). Current interest in CpG methylation arises from three kinds of observations. First, the presence or absence of cytosine methylation determines the interaction of DNA with restriction endonucleases in bacteria (Meselson et al. 1972; Mann and Smith 1978), and this has encouraged speculation that protein-DNA interactions are similarly controlled in eukaryotes (Holliday and Pugh 1975; Riggs 1975). Second, there is evidence that the pattern of DNA methylation in a cell can be inherited by its daughter cells (for review, see Wigler 1981). The idea of a heritable, but reversible, switch on the DNA has obvious attractions. Finally, tissue-specific alterations in the methylation pattern of several genes have been observed. In general, the...
