  The molecular chaperone Hsp70 plays a central role in the import of
cytoplasmic proteins into organelles, driving their translocation by binding
them from the organellar interior. Starting from the experimentally-determined
structure of the \textit{E. coli} Hsp70, we computed, by means of molecular
simulations, the effective free-energy profile for substrate translocation upon
chaperone binding. We then used the resulting free energy to quantitatively
characterize the kinetics of the import process, whose comparison with
unassisted translocation highlights the essential role played by Hsp70 in
importing cytoplasmic proteins.
