ID   GCH1_EUGGR              Reviewed;          80 AA.
AC   P51597;
DT   01-OCT-1996, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-1996, sequence version 1.
DT   02-SEP-2026, entry version 86.
DE   RecName: Full=GTP cyclohydrolase 1;
DE            EC=3.5.4.16;
DE   AltName: Full=GTP cyclohydrolase I;
DE            Short=GTP-CH-I;
DE   Flags: Fragment;
OS   Euglena gracilis.
OC   Eukaryota; Discoba; Euglenozoa; Euglenida; Spirocuta; Euglenophyceae;
OC   Euglenales; Euglenaceae; Euglena.
OX   NCBI_TaxID=3039;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   STRAIN=Z / ATCC 12894;
RX   PubMed=7542887; DOI=10.1006/bbrc.1995.2026;
RA   Maier J., Witter K., Guetlich M., Ziegler I., Werner T., Ninnemann H.;
RT   "Homology cloning of GTP-cyclohydrolase I from various unrelated eukaryotes
RT   by reverse-transcription polymerase chain reaction using a general set of
RT   degenerate primers.";
RL   Biochem. Biophys. Res. Commun. 212:705-711(1995).
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=GTP + H2O = 7,8-dihydroneopterin 3'-triphosphate + formate +
CC         H(+); Xref=Rhea:RHEA:17473, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378,
CC         ChEBI:CHEBI:15740, ChEBI:CHEBI:37565, ChEBI:CHEBI:58462; EC=3.5.4.16;
CC   -!- ACTIVITY REGULATION: GTP shows a positive allosteric effect, and
CC       tetrahydrobiopterin inhibits the enzyme activity. {ECO:0000250}.
CC   -!- PATHWAY: Cofactor biosynthesis; 7,8-dihydroneopterin triphosphate
CC       biosynthesis; 7,8-dihydroneopterin triphosphate from GTP: step 1/1.
CC   -!- SUBUNIT: Toroid-shaped homodecamer, composed of two pentamers of five
CC       dimers. {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the GTP cyclohydrolase I family. {ECO:0000305}.
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DR   EMBL; Z49757; CAA89827.1; -; mRNA.
DR   PIR; S54909; S54909.
DR   AlphaFoldDB; P51597; -.
DR   SMR; P51597; -.
DR   UniPathway; UPA00848; UER00151.
DR   GO; GO:0005737; C:cytoplasm; IEA:TreeGrafter.
DR   GO; GO:0005525; F:GTP binding; IEA:TreeGrafter.
DR   GO; GO:0003934; F:GTP cyclohydrolase I activity; IEA:UniProtKB-EC.
DR   GO; GO:0008270; F:zinc ion binding; IEA:TreeGrafter.
DR   GO; GO:0006729; P:tetrahydrobiopterin biosynthetic process; IEA:TreeGrafter.
DR   GO; GO:0046654; P:tetrahydrofolate biosynthetic process; IEA:InterPro.
DR   FunFam; 3.30.1130.10:FF:000001; GTP cyclohydrolase 1; 1.
DR   Gene3D; 3.30.1130.10; -; 1.
DR   InterPro; IPR043133; GTP-CH-I_C/QueF.
DR   InterPro; IPR001474; GTP_CycHdrlase_I.
DR   InterPro; IPR018234; GTP_CycHdrlase_I_CS.
DR   InterPro; IPR020602; GTP_CycHdrlase_I_dom.
DR   PANTHER; PTHR11109:SF7; GTP CYCLOHYDROLASE 1; 1.
DR   PANTHER; PTHR11109; GTP CYCLOHYDROLASE I; 1.
DR   Pfam; PF01227; GTP_cyclohydroI; 1.
DR   SUPFAM; SSF55620; Tetrahydrobiopterin biosynthesis enzymes-like; 1.
DR   PROSITE; PS00860; GTP_CYCLOHYDROL_1_2; 1.
PE   2: Evidence at transcript level;
KW   Allosteric enzyme; GTP-binding; Hydrolase; Metal-binding;
KW   Nucleotide-binding; Tetrahydrobiopterin biosynthesis; Zinc.
FT   CHAIN           <1..>80
FT                   /note="GTP cyclohydrolase 1"
FT                   /id="PRO_0000119484"
FT   BINDING         4
FT                   /ligand="Zn(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29105"
FT                   /evidence="ECO:0000250"
FT   BINDING         7
FT                   /ligand="Zn(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29105"
FT                   /evidence="ECO:0000250"
FT   BINDING         75
FT                   /ligand="Zn(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29105"
FT                   /evidence="ECO:0000250"
FT   NON_TER         1
FT   NON_TER         80
SQ   SEQUENCE   80 AA;  9097 MW;  8C46A15D01A7B8C7 CRC64;
     FSMCEHHMLP FWGKVHIAYI PKGKVLGLSK LARVAEMYAR RLQVQERLTR QIASAIERSI
     QPLGVAVVVD CCHMCMVMRG
//