DNA methyltransferase

DNA methyltransferase (DNMT) is a family of enzymes that catalyze the transfer of a methyl group to DNA. DNA methylation serves a wide variety of biological functions. All the enzymes of this family use S-adenosyl methionine (SAM) as the methyl donor.

Function

DNA methylation is a crucial part of normal organismal development and cellular differentiation in higher organisms. DNA methylation stably alters the gene expression pattern in cells such that cells can "remember where they have been" - for example, DNA methylation patterns are largely erased and then re-established between generations in mammals.

Types

There are several types of DNA methyltransferase:

• DNMT1 - the maintenance methyltransferase that is responsible for copying DNA methylation patterns to the daughter strands during DNA replication.
• DNMT3 - the de novo methyltransferase that sets up DNA methylation patterns early in development.
• DNMT2 - despite its name, DNMT2 is not a DNA methyltransferase since it methylates tRNA instead of DNA.

Role in disease

Abnormal DNA methylation patterns are thought to be involved in oncogenesis. DNMTs are the enzymes responsible for the methylation of the cytosine in the CpG dinucleotide. Overexpression of these enzymes has been associated with the occurrence of certain types of cancer.

See also

• Epigenetics
• Histone methyltransferase
• Methylation

References

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DNA_methyltransferase

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  Histone tails set for transcriptional activation
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  Histone tails set for transcriptional repression