A STOCHASTIC MECHANO-CHEMICAL MODEL FOR COOPERATIVE MOTOR PROTEIN DYNAMICS

The Peskin-Oster model for single molecule experiments on kinesin is extended to analyze the motion of two motors cooperatively pulling a bead in a kinesin motility assay. The various assumptions inherent in the model are tested for the case of two motors, and justified rigorously. We formulate a Markov process similar to the single motor case, and simulate the master equations on a restricted set {-N, ... , N} for each motor. The model is simulated for different initial configurations, and motors with identical parameters are found to synchronize in expectation, both spatially and in phase. It is found that synchronization is faster at higher loads and for higher adenosine triphosphate (ATP) concentrations. From a physical perspective, it is shown that the motors move to a configuration where the load is shared equally between them.