Two steps: attach ribose 1-phosphate, then add a phosphate from ATP
Route: Uracil → Uridine → Uridine monophosphate
Uridine phosphorylase joins uracil to the ribose of ribose 1-phosphate, which gives uridine and releases phosphate. Uridine-cytidine kinase then moves a phosphate from ATP to the 5' hydroxyl of uridine, which gives UMP. The same kinase also phosphorylates cytidine. UMP can then continue to UTP and CTP as in the de novo pathway.
Practice this pathway All pathways
| Step | Enzyme | EC | In | Out |
|---|---|---|---|---|
| 1 | Uridine phosphorylase | 2.4.2.3 | Ribose 1-phosphate | Pᵢ |
| 2 | Uridine-cytidine kinase | 2.7.1.48 | ATP | ADP |
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).