NADH Dehydrogenase subunit 6 (MTND6) is 1 of the 7 mitochondrial DNA (mtDNA) encoded subunits (MTND1, MTND2, MTND3, MTND4L, MTND4, MTND5, MTND6) included among the approximately 41 polypeptides of respiratory Complex I. Complex I accepts electrons from NADH, transfers them to ubiquinone (Coenzyme Q10), and uses the energy released to pump protons across the mitochondria inner membrane. MTND6 has been proposed to be a component of the iron-protein fragment.