Metabolic pathway
Gluconeogenesis
Rebuilds glucose from pyruvate, lactate or amino acids when there is no glycogen left to spend. It runs glycolysis backwards except at three steps, which do not reverse and are bypassed with enzymes of their own.
- In
- 2 Pyruvate + 4 ATP + 2 GTP + 2 NADH + 2 Proton + 6 Water
- Out
- Glucose + 4 ADP + 2 GDP + 6 Inorganic phosphate + 2 NAD⁺
- Location
- Cytosol
Fun facts
- Pyruvate carboxylaseIt only works if acetyl-CoA has built up. That build-up means there is fuel to spare, and then it pays to store carbon as glucose instead of burning it.
- Fructose-1,6-bisphosphataseFructose-2,6-bisphosphate switches it off and at the same time switches on the opposing enzyme of glycolysis. A single molecule decides the direction of both pathways, and its concentration is set by insulin versus glucagon.
- Glucose-6-phosphataseOnly the liver and the kidney have this enzyme. That is why muscle, which stores a lot of glycogen, cannot give glucose back to the blood: it spends it itself.
Reactions
| # | Enzyme | ΔG°′ |
|---|---|---|
| 1×2 | Pyruvate carboxylaseEC 6.4.1.1 · irreversiblePyruvate + Carbon dioxide + ATP + Water → Oxaloacetate + ADP + Inorganic phosphate | −2.1kJ/molexergonic |
| 2×2 | Phosphoenolpyruvate carboxykinaseEC 4.1.1.32 · irreversibleOxaloacetate + GTP → Phosphoenolpyruvate + Carbon dioxide + GDP | 0.9kJ/molendergonic |
| 3×2 | EnolaseEC 4.2.1.11Phosphoenolpyruvate + Water ⇌ 2-Phosphoglycerate | −1.8kJ/molexergonic |
| 4×2 | Phosphoglycerate mutaseEC 5.4.2.112-Phosphoglycerate ⇌ 3-Phosphoglycerate | −4.4kJ/molexergonic |
| 5×2 | Phosphoglycerate kinaseEC 2.7.2.33-Phosphoglycerate + ATP ⇌ 1,3-Bisphosphoglycerate + ADP | 18.8kJ/molendergonic |
| 6×2 | Glyceraldehyde-3-phosphate dehydrogenaseEC 1.2.1.121,3-Bisphosphoglycerate + NADH + Proton ⇌ Glyceraldehyde 3-phosphate + NAD⁺ + Inorganic phosphate | −6.3kJ/molexergonic |
| 7 | Triose phosphate isomeraseEC 5.3.1.1Glyceraldehyde 3-phosphate ⇌ Dihydroxyacetone phosphate | −7.5kJ/molexergonic |
| 8 | AldolaseEC 4.1.2.13Glyceraldehyde 3-phosphate + Dihydroxyacetone phosphate ⇌ Fructose 1,6-bisphosphate | −23.8kJ/molexergonic |
| 9 | Fructose-1,6-bisphosphataseEC 3.1.3.11 · irreversibleFructose 1,6-bisphosphate + Water → Fructose 6-phosphate + Inorganic phosphate | −16.3kJ/molexergonic |
| 10 | Phosphoglucose isomeraseEC 5.3.1.9Fructose 6-phosphate ⇌ Glucose 6-phosphate | −1.7kJ/molexergonic |
| 11 | Glucose-6-phosphataseEC 3.1.3.9 · irreversibleGlucose 6-phosphate + Water → Glucose + Inorganic phosphate | −13.8kJ/molexergonic |
11 of 11 reactions with a documented ΔG.
Use Shift to select several
The data sheet includes the map. The logo goes at the bottom.
Sources
- Nelson, D. L. & Cox, M. M. (2021). Lehninger. Principios de bioquímica, 8.ª ed., ch. 15