This family is the gamma subunit of the nitrate reductase enzyme, the gamma subunit is a b-type cytochrome that receives electrons from the quinone pool [1]. It then transfers these via the iron-sulfur clusters of the beta subunit to the molybdenum cofactor found in the alpha subunit [1]. The nitrate reductase enzyme, EC:1.7.99.4 catalyses the conversion of nitrite to nitrate via the reduction of an acceptor. The nitrate reductase enzyme is composed of three subunits [1]. Nitrate is the most widely used alternative electron acceptor after oxygen [1].

1: Identification and characterization of the Staphylococcus carnosus nitrate reductase operon. Pantel I, Lindgren PE, Neubauer H, Gotz F; Mol Gen Genet 1998;259:105-114. PMID:9738886