Proteintransport acrossorganelles’membranes requires that precursorproteins adopt anunfoldedstructure inorder tobe translocatedby the importmachinery. Ferredoxin–NADP + reductaseprecursor, aswell asmanyothers, acquiresatightly foldedstructure thatneeds tobeunfoldedbeforeorduring its import. Several steps of chloroplast protein import are not fullyunderstood. Inparticular, the roleofdifferent regionsof the precursor protein has not been completely elucidated.