Involved in protein precursor import into chloroplasts. Part of the redox regulon consisting of TIC32, TIC 55 and TIC62. Has a NADPH-dependent dehydrogenase activity, but only after preincubation with lipids. Part of the Tic complex. Interacts with TIC40, TIC110 and TIC55. Interacts (via C-terminus) with PETH/FNR. Shuttles between the membranes and the stroma, depending on the redox state of the plastidic NADP(+)/NADPH pool. The C-terminus (346-534) is specific for the interaction with PETH/FNR. The central region (247-346) is sufficient for binding to the Tic complex. The N-terminus has a dehydrogenase activity in vitro. Dissociates from the Tic complex after addition of NADPH, while addition of NADP(+) reduces the interaction with PETH/FNR.