UniProt ID: Q7ZYW9
FUNCTION: Catalyzes the conversion of inosine 5'-phosphate (IMP) to xanthosine 5'-phosphate (XMP), the first committed and rate- limiting step in the de novo synthesis of guanine nucleotides, and therefore plays an important role in the regulation of cell growth. {ECO:0000256|HAMAP-Rule:MF_03156}.
CATALYTIC ACTIVITY: Reaction=H2O + IMP + NAD(+) = H(+) + NADH + XMP; Xref=Rhea:RHEA:11708, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:57464, ChEBI:CHEBI:57540, ChEBI:CHEBI:57945, ChEBI:CHEBI:58053; EC=; Evidence={ECO:0000256|HAMAP- Rule:MF_03156, ECO:0000256|RuleBase:RU003928};
COFACTOR: Name=K(+); Xref=ChEBI:CHEBI:29103; Evidence={ECO:0000256|HAMAP- Rule:MF_03156};
ACTIVITY REGULATION: Mycophenolic acid (MPA) is a non-competitive inhibitor that prevents formation of the closed enzyme conformation by binding to the same site as the amobile flap. In contrast, mizoribine monophosphate (MZP) is a competitive inhibitor that induces the closed conformation. MPA is a potent inhibitor of mammalian IMPDHs but a poor inhibitor of the bacterial enzymes. MZP is a more potent inhibitor of bacterial IMPDH. {ECO:0000256|HAMAP-Rule:MF_03156}.
PATHWAY: Purine metabolism; XMP biosynthesis via de novo pathway; XMP from IMP: step 1/1. {ECO:0000256|HAMAP-Rule:MF_03156, ECO:0000256|RuleBase:RU003928}.
SUBUNIT: Homotetramer. {ECO:0000256|HAMAP-Rule:MF_03156}.
SUBCELLULAR LOCATION: Cytoplasm {ECO:0000256|HAMAP-Rule:MF_03156}. Nucleus {ECO:0000256|HAMAP-Rule:MF_03156}.
SIMILARITY: Belongs to the IMPDH/GMPR family. {ECO:0000256|HAMAP- Rule:MF_03156, ECO:0000256|RuleBase:RU003927}.
CAUTION: Lacks conserved residue(s) required for the propagation of feature annotation. {ECO:0000256|HAMAP-Rule:MF_03156}.
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