Methylcobalamin, also known as methyl B12, is a form of vitamin B12 that plays a role in methylation, a process by which methyl groups are added to DNA, RNA, and proteins. This process can affect the expression of genes and can play a role in gene copying misfiring.
Methylcobalamin is a cofactor for the enzyme methionine synthase, which is responsible for converting homocysteine to methionine. Methionine is then converted to S-adenosylmethionine (SAM), which is a methyl donor that is used in many methylation reactions, including the methylation of DNA and proteins.
Methylcobalamin also plays a role in the remethylation of homocysteine to methionine, this process is very important because homocysteine can be toxic in high levels and it is associated with the development of cardiovascular diseases and neural tube defects.
Deficiency in methylcobalamin can lead to a vitamin health deficiency.