Fumarate reductase is a membrane-bound flavoenzyme consisting of four subunits, A-B. A and B comprise the membrane-extrinsic catalytic domain and C and D link the catalytic centres to the electron-transport chain. This family consists of the 13kD hydrophobic subunit D.

1: Nucleotide sequence and comparative analysis of the frd operon encoding the fumarate reductase of Proteus vulgaris. Extensive sequence divergence of the membrane anchors and absence of an frd-linked ampC cephalosporinase gene. Cole ST; Eur J Biochem 1987;167:481-488. PMID:3308458