NADPH Cytochrome P450 Oxidoreductase' ( or CYPOR) is approximately is a multimeric enzyme approximately 78kDa in size. The role of this enzyme is to shuttle electrons from NADPH via FAD and FMN to other P450 cytochromes in the endoplasmic reticulum. CYPOR contains an N-terminal α-helix that anchors it in the endoplasmic reticulum membrane. The most C-terminal domain acts to bind NADH and FAD, and the N-terminal domain before the transmembrane anchor binds FMN. The FMN and FAD binding domains are separated by a connecting domain, which plays a role in allowing conformational change during electron transfer between the two flavin-containing domains. Crystal structures indicate the FMN domain is mobile with respect to the other domains.
