Random Walk by Majority Rule and L\'evy walk

Abstract

We have studied a random walk model based on majority rule. At a given instant, the moving direction of a cargo is determined by motor coordination mediated by a tug-of-war mechanism between two kinds of competing motor proteins. We have demonstrated that the probability distribution $P(t)$ for unidirectional run time $t$ of a cargo can be remarkably described by Levy walk for $t<\gamma_u^{-1}$ as $P(t)\propto t^{-3/2} e^{-\gamma_u t}$ with $\gamma_u$ being the unbinding rate of a motor protein from microtubule. The mean squared displacement of a cargo changes from super-diffusive behavior $\langle X^2\rangle\propto t^2$ for $t<\gamma_u^{-1}$ to normal diffusion $\langle X^2\rangle\propto t$ for $t>\gamma_u^{-1}$. By considering the correlation effect in binding of a motor protein to microtubule, we have shown that Levy walk behavior of $P(t)\propto t^{-{3/2}}$ persists robustly against correlations only adding an effective cutoff time $\gamma_b/\gamma_c^2$ with $\gamma_c$ representing the amount of correlations.