Three steps from 3-phosphoglycerate, a middle compound of glycolysis
Route: 3-Phosphoglycerate → 3-Phosphohydroxypyruvate → O-Phosphoserine → Serine
The first enzyme oxidizes the hydroxyl group of 3-phosphoglycerate to a keto group, giving NADH. The second is a transamination from glutamate that needs pyridoxal phosphate, the same helper as in the alanine pathway. The third removes the phosphate with water. Serine is not essential for humans. The first enzyme, PHGDH, is found at high levels in 70% of estrogen receptor negative breast cancers. Serine is also the start of the glycine and cysteine pathways.
Practice this pathway All pathways
| Step | Enzyme | EC | In | Out |
|---|---|---|---|---|
| 1 | Phosphoglycerate dehydrogenase | 1.1.1.95 | NAD⁺ | NADH |
| 2 | Phosphoserine aminotransferase | 2.6.1.52 | Glutamate | α-KG |
| 3 | Phosphoserine phosphatase | 3.1.3.3 | H₂O | Pᵢ |
Enzyme names and EC numbers are those used on the interactive board. Checked against sources: see the claim table in the repository (tools/pathway_data/checks).