D-threo-isocitrate + NADP(+) = 2-oxoglutarate + CO2 + NADPH Binds 1 Mg(2+) or Mn(2+) ion per subunit. Inhibition of this enzyme by phosphorylation regulates the branch point between the Krebs cycle and the glyoxylate bypass, which is an alternate route that accumulates carbon for biosynthesis when acetate is the sole carbon source for growth. The phosphorylation state of this enzyme is controlled by isocitrate dehydrogenase kinase/phosphatase (AceK). Optimum temperature is above 40 degrees Celsius. Monomer. This molecule consists of two distinct domains, a small domain and a large domain. The structure of the large domain repeats a motif observed in the dimeric IDH. Such a fusional structure by domain duplication enables a single polypeptide chain to form a structure at the catalytic site that is homologous to the dimeric IDH, the catalytic site of which is located at the interface of two identical subunits. Belongs to the monomeric-type IDH family.