This family consists of the NADH-ubiquinone oxidoreductase B12 subunit proteins. NADH is the central source of electrons in the mitochondrial and bacterial respiration. NADH-ubiquinone oxidoreductase is involved in the transfer of electrons from NADH to the electron transport chain. This oxidation of NADH is coupled to proton transfer across the membrane, generating a proton motive force that is utilised for the synthesis of ATP. The function of this subunit is unclear [1].

1: Identification and primary structure of five human NADH-ubiquinone oxidoreductase subunits. Ton C, Hwang DM, Dempsey AA, Liew CC; Biochem Biophys Res Commun 1997;241:589-594. PMID:9425316