Two distinct, membrane-bound, FAD-containing enzymes are responsible for the catalysis of fumarate and succinate interconversion; fumarate reductase is used in anaerobic growth, and succinate dehydrogenase is used in aerobic growth. Anchors the catalytic components of the fumarate reductase complex to the cell inner membrane, binds quinones. Part of an enzyme complex containing four subunits: a flavoprotein (FrdA), an iron-sulfur protein (FrdB), and two hydrophobic anchor proteins (FrdC and FrdD). Belongs to the FrdC family.