Chloroplasts host photosynthesis and other essential biosynthetic reactions that sustain most life forms on Earth. It is therefore vital to understand the composition and operational mechanism of the motor that powers the import of thousands of proteins into chloroplasts. A recent model depicts this motor as an integral inner-membrane protein complex with a hetero-hexameric ATPase domain protruding into the stroma. Distinguished Research Fellow Dr. Hsou-min Li and her group at the Institute of Molecular Biology, Academia Sinica showed that FtsHi1 has its ATPase domain located outside the stromal compartment and FtsHi2 is a soluble protein. This study provides a critical foundation for structural and functional characterization of the motor complex, and has been published in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).