The 6 enzymes and 10 reactions of purine synthesis are shown in green. The 2 enzymes and 3 reactions of purine recycling are shown in blue. Enzymes are shown in bold font according to their gene symbols; metabolites are shown in regular font. Abbreviations: ADA, adenosine deaminase; ADSL, adenylosuccinate lyase; ASS, adenylosuccinate synthase; AMPD, adenylate deaminase; AMP, adenosine monophosphate; ANT, adenine-based nucleotides; APRT, adenine phosphoribosyltransferase; ATIC, AICAR transformylase/IMP cyclohydrolase; AK, adenylate kinase; CAIR, 5’-Phosphoribosyl-4-carboxy-5-aminoimidazole; FAICAR, formylaminoimidazole carboxamide ribotide; GART, phosphoribosylglycinamide formyltransferase/phosphoribosylglycinamide synthetase/phosphoribosylaminoimidazole synthetase; GDA, guanine deaminase; GMP, guanosine monophosphate; GMPS, GMP-synthase; HPRT, hypoxanthine-guanine phosphoribosyltransferase; IMP, inosine monophosphate or inosinate; IMPDH, IMP-dehydrogenase; NT5, 5’-nucleotidase; PNP, purine nucleoside phosphorylase; PAICS, phosphoribosylaminoimidazole carboxylase; PFAS, phosphoribosyl formylglycinamide synthase; PPAT, bifunctional phosphoribosylaminoimidazole carboxylase; PRA, 5-phosphoribosylamine; PRPP, phosphoribosylpyrophosphate; S-AMP, adenylosuccinate; SAICAR, succinylaminoimidazole carboxamide ribotide; XOR, xanthine oxidoreductase; XMP, xanthine monophosphate; ZMP, 5-aminoimidazole-4-carboxamide ribonucleotide.