Isocitrate dehydrogenase (IDH) enzymes catalyze the oxidative decarboxylation of isocitrate to form α-ketoglutarate within the tricarboxylic acid (TCA) cycle. Mammalian IDH1 and IDH2 are NADP-dependent enzymes that exist as obligatory homodimers. Mammalian IDH3 is a mitochondrial, NAD-dependent heterotetramer comprising two catalytic alpha subunits together with regulatory beta and gamma subunits. Whereas IDH1/IDH2 reactions are both reversible, IDH3 strictly catalyzes the forward reaction, driving the TCA cycle by supplying α-ketoglutarate from the isocitrate pool. (Adapted from PMID:28375741 and PMID:28139779.)
Notes on Group
D. melanogaster Idh is the single ortholog of mammalian IDH1 and IDH2, whereas three distinct D. melanogaster genes (Idh3a, CG3483 and CG32026) appear to encode the catalytic alpha subunit of IDH3.
Gene Group has been compiled by FlyBase curators using
the following publication(s):
Alonso et al., 2005