NADPH-binding protein (PubMed:19011764). Involved in the biosynthesis of pyridine alkaloid natural products, leading mainly to the production of anabasine, anatabine, nicotine and nornicotine, effective deterrents against herbivores with antiparasitic and pesticide properties (neurotoxins); nornicotine serves as the precursor in the synthesis of the carcinogen compound N'-nitrosonornicotine (NNN) (PubMed:19011764, PubMed:31276744). Reductase involved in a late step of tobacco alkaloid biosynthesis (PubMed:19011764). Triggers either the formation of a nicotinic acid-derived precursor or the final condensation reaction of tobacco alkaloids (PubMed:19011764). Alkaloid biosynthesis; nicotine biosynthesis. Monomer. Stimulated by jasmonic acid (MeJa) (PubMed:19011764). Induced by wounding (PubMed:32688942). Reduces capacity to produce anabasine and nicotine associated with barely detectable levels of pyridine alkaloids in leaf tissues. Belongs to the NmrA-type oxidoreductase family. Isoflavone reductase subfamily.