Fig. 1.

Depiction of DNA methylation process. DNMT transfers the methyl group to 5′ position of cytosine in the DNA sequence. SAM acts as a methyl donor in this process and it is converted to SAH. SAHH converts SAH to homocysteine by the removal of adenosine moiety. Thereafter, homocysteine either undergoes the transsulfuration pathway to form GSH or remethylated through methionine synthase enzyme and form methionine. Subsequently, methionine adenosyl transferase adds adenosine to the methionine and finally forms SAM.