Lengauer, Christoph School of Medicine, The Johns Hopkins University, Baltimore, Maryland.
Last reviewed:June 2019
Show previous versions
- Effect on gene expression
- Role in cancer
- DNA hypomethylation
- DNA hypermethylation
- Diagnostic and therapeutic implications
- Related Primary Literature
- Additional Reading
The addition of a methyl group (—CH3) to certain nucleotides in genomic DNA, which is a process having important effects on gene expression. Deoxyribonucleic acid (DNA) methylation, that is, the addition of a methyl group to the DNA molecule, is an important genetic modification and is involved in gene regulation. Besides adenine, guanine, cytosine, and thymine (which are the four bases that spell out the primary sequence of genomic DNA), DNA methylation produces a fifth base called methylcytosine. Methylcytosine is a covalent modification of DNA that is replicated when the cell divides. The enzymes that can add a methyl group to the cytosine ring to form methylcytosine (Fig. 1) are called DNA methyltransferases (DNMTs). In humans and other mammals, this type of DNA modification is imposed only on cytosines that precede a guanosine in the DNA sequence (the CpG nucleotide). In simple organisms, such as yeast and Drosophila, there is little or no DNA methylation. See also: Deoxyribonucleic acid (DNA); Enzyme; Genetics; Genomics; Nucleic acid; Nucleotide
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 10,000 highly qualified scientists and 45 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information