The Tic55 (Translocon at the inner envelope membrane of chloroplasts, 55 kDa) protein was identified in pea as a putative regulator, possibly linking chloroplast protein import to the redox state of the photosynthetic machinery. Two Tic55 homologs have been proposed to exist in Arabidopsis: atTic55-II (AT2G24820) and AtPTC52 (AT4G25650) (Protochlorophyllide-dependent Translocon Component, 52 kDa; has also been called atTic55-IV) .
