Four cysteine residues and one residue, which is either serine or threonine, are identified as likely active-site residues. Solved bacterial VKOR structures has enabled more insights into the catalytic mechanism. All VKORs are transmembrane proteins with at least three TM helices at the catalytic core. The quinone to be reduced is bound by a redox-active CXXC motif in the C-terminal helices, similar to the DsbB active site. Two other cysteines to the N-terminal are located in a loop outside of the transmembrane region; they relay electrons with a redox protein (or in the case of the bacterial homolog, its own fused domain).
The human gene for VKOR is called VKORC1 (VKOR complex subunit 1). It is the target of anticoagulantwarfarin. Its partner is a redox protein with an unknown identity. There is also a similar gene called VKORC1L1.