<p> Synonyms: Inosine-5'-monophosphate dehydrogenase, Inosinic acid dehydrogenase </p><p> IMP dehydrogenase (<db_xref db="EC" dbkey="1.1.1.205"/>,IMPDH) catalyzes the rate-limiting reaction of de novo GTP biosynthesis, the NAD-dependent reduction of IMP into XMP [<cite idref="PUB00002466"/>]. <reaction> Inosine 5-phosphate + NAD+ + H2O = xanthosine 5-phosphate + NADH </reaction> </p> <p> IMP dehydrogenase is associated with cell proliferation and is a possible target for cancer chemotherapy. Mammalian and bacterial IMPDHs are tetramers of identical chains. There are two IMP dehydrogenase isozymes in humans [<cite idref="PUB00002609"/>]. IMP dehydrogenase nearly always contains a long insertion that has two CBS domains within it and adopts a TIM barrel structure.</p>