Reaction: HPRT1 tetramer transfers phosphoribosyl group to 6MP to form 6TIMP
- in pathway: Azathioprine ADME
6-mercaptopurine (6MP) can be metabolized via three competing pathways; oxidation by xanthine oxidase (XDH), methylation by thiopurine methyl S-transferase (TPMT) and conversion by hypoxanthine-guanine phosphoribosyltransferase (HPRT1).
Hypoxanthine-guanine phosphoribosyltransferase tetramer (HPRT1) catalyzes the transfer of phosphoribosyl from 5-phosphoribosyl 1-pyrophosphate (PRPP) to 6-mercaptopurine (6MP), to form 6-thioinosine 5’-monophosphate (6TIMP) (Krenitsky et al. 1969, Xu et al. 1997). This is the metabolic branch for the formation of the pharmacologically active 6-thioguanine nucleotides (6-TGNs).
Hypoxanthine-guanine phosphoribosyltransferase tetramer (HPRT1) catalyzes the transfer of phosphoribosyl from 5-phosphoribosyl 1-pyrophosphate (PRPP) to 6-mercaptopurine (6MP), to form 6-thioinosine 5’-monophosphate (6TIMP) (Krenitsky et al. 1969, Xu et al. 1997). This is the metabolic branch for the formation of the pharmacologically active 6-thioguanine nucleotides (6-TGNs).
Reaction - small molecule participants:
PPi [cytosol]
6TIMP [cytosol]
PRPP [cytosol]
Reactome.org reaction link: R-HSA-9748951
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Reaction input - small molecules:
5-O-phosphonato-alpha-D-ribofuranosyl diphosphate(5-)
Reaction output - small molecules:
diphosphate(3-)
6-Thioinosine-5'-monophosphate(2-)
Reactome.org link: R-HSA-9748951