| SCOP class : | Membrane and cell surface proteins and peptides |
| SCOP Fold : | Heme-binding four-helical bundle |
| Superfamily : | Fumarate reductase respiratory complex transmembrane subunits |
| Family : | Succinate dehydrogenase/Fumarate reductase transmembrane subunits (SdhC/FrdC and SdhD/FrdD) |