Mutations of human cytochrome P450 reductase differentially modulate heme oxygenase-1 activity and oligomerization

► Differential affinity of P450 reductase (CYPOR) mutants to heme oxygenase-1. ► Regulation of HO-1 oligomerization by CYPOR in in vitro reconstituted system. ► Inhibition of HO-1 activity at greater than 2:1 ratios of CYPOR to HO-1. ► Disruption of HO-1 oligomerization in HEK293 cells by CYPOR.