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. Author manuscript; available in PMC: 2018 Jul 11.
Published in final edited form as: Anal Chim Acta. 2017 Apr 10;976:63–73. doi: 10.1016/j.aca.2017.04.014

Figure 6. De novo synthesis of Ser and Gly from glucose via glycolysis and the 3-phosphoglycerate (3-PG) pathway and exchanges of exogenously derived Ser and Gly via one-carbon metabolism.

Figure 6

Selected Ser and Gly exchange reactions are depicted for the cytoplasmic and mitochondrial compartments to illustrate the production of different 2H isotopologues of Gly and Ser in Figs. 7 and 8. For example, the serine hydroxymethyl transferase (SHMT) reaction was shown for the cytoplasm (SHMT1) but omitted for the mitochondria (SHMT2) [10, 46]. Blue text blocks depict the de novo synthesis carbon pathway from 13C6-glucose while green and beige text blocks respectively depict the hydrogen exchange pathway of Gly and Ser via 1-carbon metabolism catalyzed by SHMT1, glycine decarboxylase complex (GLDC), and methylenetetrahydrofolate dehydrogenase (MTHFD). PHGDH: phosphoglycerate dehydrogenase; PSAT1: phosphoserine amino transferase 1; MTHFD2: mitochondrial NAD+-dependent methylene tetrahydrofolate dehydrogenase/methylene tetrahydrofolate cyclohydrolase; MTHFD2L: mitochondrial NADP+-dependent methylene tetrahydrofolate dehydrogenase.