Definitions
- Methylation: a process by which methyl groups are added to the DNA molecule
Features
- can change the activity of a DNA region without changing the sequence
- in the promoter, DNA methylation represses gene transcription
- cytosine and adenine can be methylated mostly
- GC- and CpG-rich sequences called CpG islands
- CpG island is methylated in higher ratios, caused by the high cytosine content
- 50% of CpG islands are located in gene promoter regions
- DNA methylation is the most stable (heritable) epigenetic mark
- Transcription activation: