The QSOX ψErv/Erv module resembles a baculovirus Erv enzyme. The structure of the H. sapiens QSOX sulfhydryl oxidase module  is compared with one subunit of the baculovirus Ac92 sulfhydryl oxidase dimer . Helices are represented as cylinders, the FAD is in orange sticks, and the FAD-proximal redox-active disulfide is indicated in ball-and-stick format and labeled CXXC.
Limor-Waisberg et al. BMC Evolutionary Biology 2013 13:70 doi:10.1186/1471-2148-13-70