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ENZYME entry: EC

Accepted Name
RNA 3'-terminal-phosphate cyclase (GTP).
Alternative Name(s)
RNA-3'-phosphate cyclase (GTP).
Reaction catalysed
GTP + (RNA)-3'-(3'-phospho-ribonucleoside) <=> GMP + diphosphate + (RNA)-3'-(2',3'-cyclophospho)-ribonucleoside
  • The enzyme, which is specific for GTP, was characterized from the archaeon Pyrococcus furiosus.
  • The enzyme converts the 3'-terminal phosphate of various RNA substrates into the 2',3'-cyclic phosphodiester in a GTP-dependent reaction.
  • Catalysis occurs by a three-step mechanism, starting with the activation of the enzyme by GTP, forming a phosphoramide bond between guanylate and a histidine residue.
  • The guanylate group is then transferred to the 3'-phosphate terminus of the substrate, forming the capped structure (RNA)- 3'-(5'-diphosphoguanosine).
  • Finally, the enzyme catalyzes an attack of the vicinal O-2' on the 3'-phosphorus, which results in formation of cyclic phosphate and release of the guanylate.
  • Cf. EC
PRIAM enzyme-specific profiles6.5.1.5
KEGG Ligand Database for Enzyme Nomenclature6.5.1.5
IUBMB Enzyme Nomenclature6.5.1.5
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