This is a family of integral membrane proteins including Rhodobacter-specific nitrogen fixation (rnf) proteins RnfA and RnfE [1] and Na+-translocating NADH:ubiquinone oxidoreductase (Na+-NQR) subunits NqrD and NqrE.

1: Overexpression in Escherichia coli of the rnf genes from Rhodobacter capsulatus--characterization of two membrane-bound iron-sulfur proteins. Jouanneau Y, Jeong HS, Hugo N, Meyer C, Willison JC; Eur J Biochem 1998;251:54-64. PMID:9492268