Simulation studies of protein translocation in mitochondria

Two mechanisms for the import of preproteins into mitochondria have been investigated. Both, the ratchet model of import and that of a molecular motor pulling on the preprotein, have been modelled by the introduction of appropriate force fields. Monte Carlo computer simulations of the transport of the preproteins, aided by the heat shock protein molecules, through channels in the membranes have been carried out. The translocation times were determined as a function of the strength of the force fields and temperature of the simulations. The translocation times obtained with the ratchet model were found to be much more strongly dependent on temperature than that from the hand-over-hand motor pulling mechanism.