Reaction: CAIR + Aspartate + ATP => SAICAR + ADP + Pi
- in pathway: Purine ribonucleoside monophosphate biosynthesis
The conversion of 5'-phosphoribosyl-5-aminoimidazole-4-carboxylate (CAIR) and aspartate to 5'-phosphoribosyl-5-aminoimidazole-4-N-succinocarboxamide (SAICAR), accompanied by the conversion of ATP to ADP and orthophosphate, is catalyzed by the phosphoribosylaminoimidazole succinocarboxamide synthetase 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:
Pi [cytosol]
H+ [cytosol]
ADP [cytosol]
SAICAR [cytosol]
ATP [cytosol]
L-Asp [cytosol]
CAIR [cytosol]
Reactome.org reaction link: R-HSA-73805
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Reaction input - small molecules:
ATP(4-)
L-aspartate(1-)
5-amino-1-(5-phosphonato-D-ribosyl)imidazolium-4-carboxylate(2-)
Reaction output - small molecules:
hydrogenphosphate
hydron
ADP(3-)
SAICAR(4-)
Reactome.org link: R-HSA-73805