<p>NAD(P)H-quinone oxidoreductase or NAD(P)H dehydrogenase 1 subunit D shuttles electrons from NADH, via FMN and iron-sulphur (Fe-S) centres, to quinones in the respiratory chain. The immediate electron acceptor for the enzyme in this species is believed to be ubiquinone. It couples the redox reaction to proton translocation (for every two electrons transferred, four hydrogen ions are translocated across the cytoplasmic membrane), and thus conserves the redox energy in a proton gradient.</p><p>This subunit is known as subunit H in chloroplasts and cyanobacteria. In chloroplasts NDH shuttles electrons from NAD(P)H:plastoquinone, via FMN and iron-sulphur (Fe-S) centres, to quinones in the photosynthetic chain and possibly in a chloroplast respiratory chain. The immediate electron acceptor for the enzyme in this species is believed to be plastoquinone. In cyanobacteria NDH-1 shuttles electrons from an unknown electron donor, via FMN and iron-sulphur (Fe-S) centres, to quinones in the respiratory and/or the photosynthetic chain.The immediate electron acceptor for the enzyme in this species is believed to be plastoquinone.</p><p>This subunit often appears as a subunit C/D fusion.</p>