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 LFNR1. 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 LFNR1 and LFNR2; LIR1 increases the affinity of LFNR1 and LFNR2 for TIC62 and subsequent thylakoid relocalization (By similarity). More abundant in the soluble fraction. The presence of LFNR1 is required for association with the thylakoid membrane. Expressed in shoots. Restricted to green tissues, being more abundant in stems. By nitrate. May form interchain disulfide bonds with LIR1. Belongs to the ferredoxin--NADP reductase type 1 family.