Reaction: AIR + CO2 => CAIR
- in pathway: Purine ribonucleoside monophosphate biosynthesis
The reversible carboxylation of 5'-phosphoribosyl-5-aminoimidazole (AIR) to form 5'-phosphoribosyl-5-aminoimidazole-4-carboxylate (CAIR) is catalyzed by the phosphoribosylaminoimidazole carboxylase domain of the bifunctional protein "phosphoribosylaminoimidazole carboxylase, phosphoribosylaminoimidazole succinocarboxamide synthetase" (PAICS) (Schild et al. 1990). The enzyme is an octamer (Li et al. 2007); it may associate in the cytosol with other enzymes of de novo IMP biosynthesis under some metabolic conditions (An et al. 2008).
Reaction - small molecule participants:
H+ [cytosol]
CAIR [cytosol]
AIR [cytosol]
CO2 [cytosol]
Reactome.org reaction link: R-HSA-73806
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Reaction input - small molecules:
5-amino-1-(5-phosphonato-beta-D-ribosyl)imidazol-3-ium
carbon dioxide
Reaction output - small molecules:
hydron
5-amino-1-(5-phosphonato-D-ribosyl)imidazolium-4-carboxylate(2-)
Reactome.org link: R-HSA-73806