Protein import into chloroplasts

Chloroplasts are organelles of endosymbiotic origin, and they transferred most of their genetic information to the host nucleus during this process. They therefore have to import more than 95% of their protein complement post-translationally from the cytosol. In vivo results from the model plant Arabidopsis thaliana - together with biochemical, biophysical and structural data from other plants - now allow us to outline the mechanistic details of the molecular machines that facilitate this translocation. It has become clear that chloroplasts evolved a unique translocation system, which is inherited, in part, from their bacterial ancestors.