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The annotation and conditions in this rule are derived from the following entries: Q58185 (MPTA_METJA), P94398 (GCH4_BACSU), Q5F9K6 (GCH4_NEIG1), Q9WXP6 (GCH4_THEMA)

If a protein meets these conditions... i

Common conditions

    • Matches HAMAP signature MF_01527_A
    • taxon = Archaea
    • fragment ≠ the sequence is fragmented

Special conditions

... then these annotations are applied i

Protein namesi

  • Recommended name:
    GTP cyclohydrolase MptA (EC:
    Alternative name(s):
    GTP cyclohydrolase IV
  • Recommended name:
    GTP cyclohydrolase FolE2 (EC:

Gene namesi

  • Name:mptA
  • Name:folE2

Subunit structurei

  • Homodimer.

Sequence similaritiesi


Catalytic activityi

  • GTP + H2O = formate + 7,8-dihydro-D-neopterin 2',3'-cyclic phosphate + diphosphate.
  • GTP + H2O = formate + 2-amino-4-hydroxy-6-(erythro-1,2,3-trihydroxypropyl)-dihydropteridine triphosphate.


  • Converts GTP to 7,8-dihydro-D-neopterin 2',3'-cyclic phosphate, the first intermediate in the biosynthesis of coenzyme methanopterin.
  • Converts GTP to 7,8-dihydroneopterin triphosphate.


  • Fe2+Note: Binds 1 Fe2+ ion per subunit.


  • May be catalytically important (to residues corresponding to position 160)
  • May be catalytically important (to residues corresponding to position 183)


GO (Gene Ontology) termsi

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