This enzyme is required for electron transfer from NADP to cytochrome P450 in microsomes. It can also provide electron transfer to heme oxygenase and cytochrome B5. Reduces a variety of substrates in vitro, such as cytochrome c, feericyanide and dichloroindophenol. NADPH + 2 oxidized [cytochrome P450] = H(+) + NADP(+) + 2 reduced [cytochrome P450] Binds 1 FAD per monomer. Binds 1 FMN per monomer. Expressed in roots, leaves, stems, flowers and siliques. By wounding and transition from dark to light. May be due to a competing donor splice site. Belongs to the NADPH--cytochrome P450 reductase family. In the N-terminal section; belongs to the flavodoxin family. In the C-terminal section; belongs to the flavoprotein pyridine nucleotide cytochrome reductase family.