<p>This domain is found in sulphite reductase, NADPH cytochrome P450 reductase, nitric oxide synthase and methionine synthase reductase. Flavoprotein pyridine nucleotide cytochrome reductases [<cite idref="PUB00002674"/>] (FPNCR) catalyse the interchange of reducing equivalents between one-electron carriers and the two-electron-carrying nicotinamide dinucleotides. The enzymes include ferredoxin:NADP⁺reductases (FNR) [<cite idref="PUB00002370"/>], plant and fungal NAD(P)H:nitrate reductases [<cite idref="PUB00002674"/>, <cite idref="PUB00010574"/>], NADH:cytochrome b5 reductases [<cite idref="PUB00002328"/>], NADPH:P450 reductases [<cite idref="PUB00005367"/>], NADPH:sulphite reductases [<cite idref="PUB00002509"/>], nitric oxide synthases [<cite idref="PUB00004098"/>], phthalate dioxygenase reductase [<cite idref="PUB00005007"/>], and various other flavoproteins.</p> FAD-binding, type 1