Reaction: GCH1 reduces GTP to dihydroneopterin triphosphate
The first and rate-limiting enzyme in tetrahydrobiopterin de novo biosynthesis is GTP cyclohydrolase I (GCH1, GTPCHI). Three different isoforms are produced but only isoform 1 is functionally active (Gütlich et al. 1994). GCH1 is functional as a homodecamer. First, a monomer of GCH1 forms a dimer. Then five dimers arrange into a ring-like structure to form the homodecamer (Nar et al. 1995).
Reaction - small molecule participants:
DHNTP [cytosol]
HCOOH [cytosol]
GTP [cytosol]
H2O [cytosol]
Reactome.org reaction link: R-HSA-1474146
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Reaction input - small molecules:
GTP(4-)
water
Reaction output - small molecules:
7,8-dihydroneopterin 3'-triphosphate(4-)
formate
Reactome.org link: R-HSA-1474146