Abstract
The motilities of microtubule-based motor proteins, kinesin and dynein, are investigated with vibrating ratchet-based simulation systems. These two motor proteins are reported being able to transport cargos along microtubule. Most dynamic features are established with reasonable explanations for the simulating kinesin and dynein on the asymmetric ratchet plate which is similar to the outer surface of microtubule. Kinesin motor is composed of the head domain binding to microtubule, the tail domain holding cargos, and the stalk domain connecting the two heads and the tail domains. We propose a new dynamic model for kinesin. According to the recent AFM results that the stalk domain lies sideward to on microtubule, we consider the force is generated by the randomly moving stalk on microtubule. The force produces greater tension on the trailing head than the leading head. The trailing head can be randomly triggered to flip over the leading head, processing a similar hand-over-hand motion. Otherwise, the inchworm type of motion is also possible under the influence of stochastic force. As for dynein, in our model, the force is believed to be originated from the collision between the linker and the outer surface of microtubule. The bidirectional motion, processive stepping, the velocity-force relation, and the ATP concentration dependence of velocity for dynein on microtubule are demonstrated with the simulation system. The ratchet-based simulation systems for microtubule-based motor proteins give an alternative approach to investigate the motility of kinesin and dynein.