Fig. 5.

Interconnection between glycolysis, serine biosynthesis, one-carbon metabolism, and methionine cycle. 3PG produced during glycolysis enters the serine synthesis pathway, a series of reactions that produce serine. Serine can then be converted to glycine thanks to the SHMT enzyme. Glycine participates in the folate cycle to generate additional one-carbon units. Folate is necessary for the methionine cycle, in which methionine is precursor of SAM, the methyl donor used by DNMTs to methylate DNA and histones. One-carbon metabolism comprised folate cycle and methionine cycle. Abbreviations: 3PG = 3-phosphoglycerate; SHMT = serine hydroxy methyltransferase; hCysteine = homocysteine