Isocitrate dehydrogenases catalyze the oxidative decarboxylation of isocitrate to 2-oxoglutarate. These enzymes belong to two distinct subclasses, one of which utilizes NAD(+) as the electron acceptor and the other NADP(+). Five isocitrate dehydrogenases have been reported: three NAD(+)-dependent isocitrate dehydrogenases, which localize to the mitochondrial matrix, and two NADP(+)-dependent isocitrate dehydrogenases, one of which is mitochondrial and the other predominantly cytosolic. NAD(+)-dependent isocitrate dehydrogenases catalyze the allosterically regulated rate-limiting step of the tricarboxylic acid cycle. Each isozyme is a heterotetramer that is composed of two alpha subunits, one beta subunit, and one gamma subunit. The protein encoded by this gene is the alpha subunit of one isozyme of NAD(+)-dependent isocitrate dehydrogenase.IDH3A (Isocitrate Dehydrogenase 3 (NAD(+)) Alpha) is a Protein Coding gene. Among its related pathways are Citrate cycle (TCA cycle) and Pyruvate metabolism and Citric Acid (TCA) cycle. GO annotations related to this gene include magnesium ion binding and oxidoreductase activity, acting on the CH-OH group of donors, NAD or NADP as acceptor.