Figure 1
l-Glutamate is involved in the GABA shunt (blue arrows) off of the Krebs cycle and in the glutamate-glutamine cycle (red arrows) (A). Glutamate amidation proceeds primarily in astrocytes (blue font), while the reverse reaction occurs in neurons (orange font). For simplicity the transport steps are not shown. Hypothetical metabolic scheme of 2MeGlu into methyl analogues of Glu metabolites (B). SA and α-KG have no exact analogues and are not shown in the figure. AKR aldo–keto reductase, AST aspartate transaminase, GABA-T GABA transaminase, GAD glutamate decarboxylase, GHBDH gamma-hydroxybutyrate dehydrogenase, GLDH glutamate dehydrogenase, GLS glutaminase, GS glutamine synthetase, SSADH succinic semialdehyde dehydrogenase, GABA γ-aminobutyric acid, GHB γ-hydroxybutyric acid, Gln l-glutamine, Glu l-glutamate, α-KG α-ketoglutarate, SA succinic acid, SSA succinic semialdehyde.
