Fold: Heme-binding four-helical bundle [81344]
core: four transmembrane helices, up-and-down bundle, binds one or two heme groups in between the helices
Superfamilies:
Transmembrane di-heme cytochromes [81342] (2) Three of the four heme-ligands are conserved between the two families; both heme groups bind similarly but not identically uperfamily
Respiratory nitrate reductase 1 gamma chain [103501] (1) possible link between the two other superfamilies: this subunit corresponds to the gamma subunit of a functionally related Formate dehydrogenase N complex but is structurally closer to the Fumarate reductase subunit FrdC uperfamily