Methyl group transfer pathway

Methyl group transfer pathways refer broadly to a set of interconnected biochemical cycles responsible for the transfer of methyl groups (–CH₃) to diverse substrates, including DNA, RNA, proteins (especially histones), and small molecules. These reactions are catalyzed primarily by *methyltransferases*, which use S-adenosylmethionine (SAM) as the universal methyl donor[1][2][3][4][5]. The methionine → SAM → S-adenosylhomocysteine (SAH) → homocysteine cycle is central to methyl group supply and recycling in cells, often termed the "SAM cycle" or one-carbon metabolism[1][3]. Methyl group transfer is crucial for epigenetic regulation, influencing gene expression, chromatin structure, and cellular differentiation[1][2][7]. Disruption of these pathways, whether by genetic variants or nutritional deficiencies (e.g., folate or vitamin B₁₂), has been linked to diseases such as cancer, neural tube defects, and neuropsychiatric conditions[3][7]. Because "methyl group transfer pathway" refers to a collection of processes and not a specific molecule, enzyme, or druggable target, it is **not considered a therapeutic target** per se—although individual enzymes (like DNA methyltransferases or protein methyltransferases) within these pathways are well-established drug targets in oncology and epigenetics[2][4][7]. **Note:** "Methyl group transfer pathways" are not a single molecular target, but rather a functional class or set of metabolic/epigenetic processes. For structured data systems, one should identify specific methyltransferase enzymes or methylation targets (e.g., DNA methyltransferase 1, protein arginine methyltransferase 5, etc.) for drug targeting or biomarker purposes.

Other names

Methylation pathwaySAM cycleTransmethylation pathwayOne-carbon metabolism