|PROSITE documentation PDOC00391|
IMP dehydrogenase (EC 18.104.22.168) (IMPDH) catalyzes the rate-limiting reaction of de novo GTP biosynthesis, the NAD-dependent reduction of IMP into XMP . Inhibition of IMP dehydrogenase activity results in the cessation of DNA synthesis. As IMP dehydrogenase is associated with cell proliferation, it is a possible target for cancer chemotherapy. Mammalian and bacterial IMPDHs are tetramers of identical chains. There are two IMP dehydrogenase isozymes in humans .
GMP reductase (EC 22.214.171.124) catalyzes the irreversible and NADPH-dependent reductive deamination of GMP into IMP . It converts nucleobase, nucleoside and nucleotide derivatives of G to A nucleotides, and maintains intracellular balance of A and G nucleotides.
IMP dehydrogenase and GMP reductase share many regions of sequence similarity. One of these regions is centered on a cysteine residue thought  to be involved in binding IMP. We have used this region as a signature pattern.Last update:
December 2004 / Pattern and text revised.
PROSITE method (with tools and information) covered by this documentation:
|1||Authors||Collart F.R., Huberman E.|
|Title||Cloning and sequence analysis of the human and Chinese hamster inosine-5'-monophosphate dehydrogenase cDNAs.|
|Source||J. Biol. Chem. 263:15769-15772(1988).|
|2||Authors||Natsumeda Y., Ohno S., Kawasaki H., Konno Y., Weber G., Suzuki K.|
|Title||Two distinct cDNAs for human IMP dehydrogenase.|
|Source||J. Biol. Chem. 265:5292-5295(1990).|
|3||Authors||Andrews S.C., Guest J.R.|
|Title||Nucleotide sequence of the gene encoding the GMP reductase of Escherichia coli K12.|
|Source||Biochem. J. 255:35-43(1988).|