Reaction velocity plots of BTC3A4_POR membranes. A, velocity plots of human liver microsomes versus BTC3A4_PORWT membranes with DBF up to 1.25 μM. B, velocity plots of BTC3A4_POR membranes containing CYPOR variants WT, Q153R, Y181D, M263V, or A287P with DBF up to 5 μM. C, velocity plots of BTC3A4_POR membranes containing CYPOR variants WT or Q153R, using DBF gradient up to 10 μM. D, velocity plots of BTC3A4 membranes containing CYPOR variants WT, Q153R, or A287P with DBOMF.