{PDOC00672}
{PS00859; GTP_CYCLOHYDROL_1_1}
{PS00860; GTP_CYCLOHYDROL_1_2}
{BEGIN}
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* GTP cyclohydrolase I signatures *
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GTP cyclohydrolase  I  (EC 3.5.4.16) catalyzes the biosynthesis of formic acid
and dihydroneopterin triphosphate from GTP. This reaction is the first step in
the biosynthesis of tetrahydrofolate in prokaryotes, of tetrahydrobiopterin in
vertebrates, and of pteridine-containing pigments in insects.

GTP cyclohydrolase  I is a protein of from 190 to 250 amino acid residues. The
comparison of the sequence of the enzyme from bacterial and eukaryotic sources
shows that  the  structure  of  this  enzyme has been extremely well conserved
throughout evolution [1].

As signature patterns we selected two conserved regions.  The first contains a
perfectly conserved  tetrapeptide which is part of the GTP-binding pocket [2],
the second region also contains conserved residues involved in GTP-binding.

-Consensus pattern: [DENGQST]-[LIVMPF]-[LIVM]-x(1,2)-[KRNQELD]-[DENKGS]-
                    [LIVM]-x(3)-[STG]-x-C-[EP]-H(2)
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Consensus pattern: [SA]-x-[RK]-x-Q-[LIVMT]-Q-E-[RNAK]-[LIM]-[TSNV]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Last update: April 2006 / Pattern revised.

[ 1] Maier J., Witter K., Gutlich M., Ziegler I., Werner T., Ninnemann H.
     "Homology cloning of GTP-cyclohydrolase I from various unrelated
     eukaryotes by reverse-transcription polymerase chain reaction using a
     general set of degenerate primers."
     Biochem. Biophys. Res. Commun. 212:705-711(1995).
     PubMed=7542887
[ 2] Nar H., Huber R., Meining W., Schmid C., Weinkauf S., Bacher A.
     "Atomic structure of GTP cyclohydrolase I."
     Structure 3:459-466(1995).
     PubMed=7663943

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