May function in the production of NADPH for fatty acid and sterol synthesis. D-threo-isocitrate + NADP(+) = 2-oxoglutarate + CO2 + NADPH Binds 1 Mg(2+) or Mn(2+) ion per subunit. By catabolite repression. Homodimer. The N-terminus is blocked. Present with 2620 molecules/cell in log phase SD medium. Belongs to the isocitrate and isopropylmalate dehydrogenases family.