NDH-1 shuttles electrons from NADH, via FMN and iron-sulfur (Fe-S) centers, to quinones in the respiratory chain. The immediate electron acceptor for the enzyme in this species is believed to be ubiquinone. 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. a quinone + 5 H(+)(in) + NADH = a quinol + 4 H(+)(out) + NAD(+) NDH-1 is composed of at least 14 different subunits, Nqo1 to Nqo14. The complex has a L-shaped structure, with the hydrophobic arm (subunits Nqo7, Nqo8, Nqo10 to Nqo14) embedded in the inner membrane and the hydrophilic peripheral arm (subunits Nqo1 to Nqo6, Nqo9) protruding into the bacterial cytoplasm. The hydrophilic domain contains all the redox centers (By similarity). NADH-quinone oxidoreductase forms a supercomplex with ubiquinol-cytochrome c reductase complex (complex III or cytochrome b-c1 complex) and cytochrome c oxidase (complex IV), which stabilizes the NADH-quinone oxidoreductase complex (PubMed:14610094). Belongs to the complex I 49 kDa subunit family.