Distribution of Na⁺-NQR and RNF in Archaea and Bacteria.

Please note that although the nqr and rnf operons were found in these phyla, there is a large variability among the bacterial orders and some of them might not contain any of the two complexes. Moreover, the presence of the genes might not indicate that the complexes are functional and further biochemical characterizations are necessary to clarify these and other aspects.