Which of the following does not or permissive euchromatin due to changes occurring at cytosine residues at CpG islands in DNA?
(A) Methylation (B) Alkylation (C) Phosphorylation (D) Sumoylation
(A) Ans: A. Methylationref: Harper's illustrated biochemistry, 30th editon., pg. 560.Methylation of cpG sites in the promoter of a gene may inhibit gene expression.There is also evidence that low folate status results in impaired methylation of cpG islands in DNA, which is a factor in the development of colorectal and other cancers.