IDH3G, also known as isocitrate dehydrogenase [NAD] subunit gamma, mitochondrial, belongs to the isocitrate and isopropylmalate dehydrogenases family. Isocitrate dehydrogenases catalyze the oxidative decarboxylation of isocitrate to 2-oxoglutarate. IDH3G is a gamma subunit of one isozyme of isocitrate dehydrogenase that belongs to a distinct subclass, which utilizes NAD(+) as the electron acceptor, and is localised to the mitochondrial matrix.