Question

What does methylation do to gene expression?

Answer 1

DNA methylation:

1. DNA methylation is the addition of a methyl group (CH₃) to the covalent nitrogen-base (C) cytosine at the 5′CpG3′ positions.
2. The CpG site is a region of DNA where the cytosine nucleotide is followed by the guanine nucleotide along with the 5' to 3' direction of the straight DNA strand.
3. Cytosine is linked to the guanine nucleotide via a phosphate (p) group.
4. DNA methylation is regulated by DNA methyltransferase.
5. Epigenetic marking of CpG sites in the genome is species-specific.
6. In the human genome, many CpG sites are methylated.

Function:

1. The main function of DNA methylation is to regulate gene expression according to the needs of a particular cell.
2. Methylated CpG sites attract methyl CpG binding domain proteins, recruiting the repressor complexes responsible for the histone modification.
3. DNA methylation patterns are very stable and specific to specific cells.
4. DNA methylation involves tissue-specific gene expression, X-chromosome inactivation, and genomic imprinting.