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Ferredoxin reductase-like proteins catalyze electron transfer between an NAD(P)-binding domain of the alpha/beta class and a discrete (usually N-terminal) domain which varies in orientation with respect to the NAD(P) binding domain. The N-terminal region may contain a flavin prosthetic group (as in flavoenzymes) or use flavin as a substrate. Ferredoxin is reduced in the final stage of photosystem I. The flavoprotein Ferredoxin-NADP+ reductase transfers electrons from reduced ferredoxin to FAD (forming FADH2 via a semiquinone intermediate) which then transfers a hydride ion to convert NADP+ to NADPH.