Plays a key role in regulating the relative amounts of cyclic and non-cyclic electron flow to meet the demands of the plant for ATP and reducing power. H(+) + NADP(+) + 2 reduced [2Fe-2S]-[ferredoxin] = NADPH + 2 oxidized [2Fe-2S]-[ferredoxin] Energy metabolism; photosynthesis. Heterodimer with LFNR2. Interacts with PGRL1A and PGRL1B. Interacts with TIC62. Component of high molecular weight thylakoid LFNRs-containing protein complexes containing LIR1, LFNR1, LFNR2, TIC62 and TROL proteins. Interacts directly with LIR1 and TIC62; LIR1 increases the affinity of LFNR1 and LFNR2 for TIC62 (By similarity). More abundant in the membrane fraction. A number of isoforms are produced. According to EST sequences. Expressed in shoots. Restricted to green tissues, being more abundant in siliques. By nitrate. May form interchain disulfide bonds with LIR1. Plants have a reduced capacity for carbon fixation and prevent the association of LFNR2 with the thylakoid membrane. Belongs to the ferredoxin--NADP reductase type 1 family.