CAIR + Aspartate + ATP => SAICAR + ADP + Pi

Stable Identifier
Homo sapiens
5'-phosphoribosyl-5-aminoimidazole-4-carboxylate (CAIR) + L-aspartate + ATP => 5'-phosphoribosyl-5-aminoimidazole-4-N-succinocarboxamide (SAICAR) + ADP + orthophosphate
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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).

Literature References
PubMed ID Title Journal Year
18388293 Reversible compartmentalization of de novo purine biosynthetic complexes in living cells

Benkovic, SJ, Sheets, ED, Kumar, R, An, S

Science 2008
2183217 Cloning of three human multifunctional de novo purine biosynthetic genes by functional complementation of yeast mutations

Brake, AJ, Kiefer, MC, Schild, D, Young, D, Barr, PJ

Proc Natl Acad Sci USA 1990
17224163 Octameric structure of the human bifunctional enzyme PAICS in purine biosynthesis

Xie, XC, Wang, QH, Tong, YP, Li, SX, Li, SG, Zhang, ZY, Bi, RC, Zhou, HN, Zhang, XC, Gao, W, Han, Y

J Mol Biol 2007
Catalyst Activity

phosphoribosylaminoimidazolesuccinocarboxamide synthase activity of PAICS octamer [cytosol]

Orthologous Events
Cross References
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