This MedLibrary.org supplementary page on 5-Methylcytosine is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
| 5-Methylcytosine | |
|---|---|
 |
|
| IUPAC name | 4-amino-5-methyl-3H-pyrimidin-2-one |
| Identifiers | |
| CAS number | 554-01-8 |
| PubChem | |
| MeSH | |
| SMILES |
|
| Properties | |
| Molecular formula | C5H7N3O |
| Molar mass | 125.129 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references |
|
5-Methylcytosine is a methylated form of cytosine in which a methyl group is attached to carbon 5, altering its structure without altering its base-pairing properties.
Contents |
In vivo
5-Methylcytosine is an epigenetic modification formed by the action of DNA methyltransferases. Its function varies significantly among species:1
- In bacteria, 5-methylcytosine can be found at a variety of sites, and is often used as a marker to protect DNA from being cut by native methylation-sensitive restriction enzymes.
- In plants, 5-methylcytosine occurs at CpG, CpNpG and CpNpN sequences (where N = A, C or T).
- In fungi and animals, 5-methylcytosine predominantly occurs at CpG dinucleotides. Although most eukaryotes methylate only a small percentage of these sites, in vertebrates 70-80% of CpG cytosines are methylated.
While spontaneous deamination of cytosine forms uracil, which is recognized and removed by DNA repair enzymes, deamination of 5-methylcytosine forms thymine. This conversion of a DNA base from cytosine (C) to thymine (T) can result in a transition mutation.
In vitro
5-Methylcytosine can be deaminated to form thymine with use of reagents such as nitrous acid; cytosine deaminates to uracil under similar conditions.
5-Methylcytosine is resistant to deamination by bisulfite treatment, which deaminates cytosine residues; this property is often exploited to analyze DNA cytosine methylation patterns with bisulfite sequencing.2
Additional images
References
- ^ Colot V, Rossignol JL (1999). "Eukaryotic DNA methylation as an evolutionary device". Bioessays 21 (5): 402–11. doi:. PMID 10376011.
- ^ Clark SJ, Harrison J, Paul CL, Frommer M (1994). "High sensitivity mapping of methylated cytosines". Nucleic Acids Res. 22 (15): 2990–7. PMID 8065911.
- Griffiths, Anthony J. F. (1999). An Introduction to genetic analysis. San Francisco: W.H. Freeman, Chapter 15: Gene Mutation. ISBN 0-7167-3520-2. (available online at the United States National Center for Biotechnology Information)
Wikipedia content modification information:
- This page was last modified on 4 October 2008, at 17:30.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "5-Methylcytosine".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.