unreviewed

Ribonucleotide reductase (RNR)

1 reactions · 1 pathways

Clinical / pharmacological. Target of hydroxyurea; allosterically controlled by dNTPs

What it does, reaction by reaction

1 reactions

Pyrimidine De Novo Synthesis (through to UMP, then CTP/dTMP) Nucleotide Metabolism · Cytosol (one mitochondrial step)

step 10 Irreversible/directional

UDP → dUDP (route to dUMP)

Converts UDP into dUDP

› Notes

Ribonucleotide reductase (RNR) catalyzes UDP + reducing equivalents → dUDP + oxidized electron-transfer proteins. In humans the reducing equivalents are supplied principally by NADPH through thioredoxin reductase and thioredoxin (or through glutaredoxin/glutathione); RNR is covered mechanistically in the deoxyribonucleotide section.

Showing all 1 reactions.

What accelerates and inhibits it

Regulation is pathway-specific, so each context is listed separately

1 entries

Deoxyribonucleotide Formation (Ribonucleotide Reductase pathway and thymidylate synthesis)

Accelerated by

ATP at the activity site; substrate specificity is directed by ATP/dATP, dTTP, and dGTP at the specificity site

Inhibited by

dATP at the activity site (global feedback inhibition); hydroxyurea quenches the radical; iron limitation impairs radical-center assembly

Hormonal control

Transcription and activity rise in late G1/S through E2F and proliferative growth-factor signaling; p53-induced RRM2B supports DNA repair under stress.

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