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 14 different subunits. Subunits NuoA, H, J, K, L, M, N constitute the membrane sector of the complex (Probable). No functional NADH-quinone oxidoreductase complex. Cells lacking this gene have a nearly normal respiratory growth phenotype on lactate, however they are unable to perform anaerobic photosynthesis. It is suggested that in R.capsulatus this complex may function in reverse flow under physiological conditions. Belongs to the complex I subunit 5 family.