title: Bidirectional transport in a multispecies totally asymmetric exclusion-process model.
abstract: We study a minimal lattice model which describes bidirectional transport of "particles" driven along a one-dimensional track, as is observed in microtubule based, motor protein driven bidirectional transport of cargo vesicles, lipid bodies, and organelles such as mitochondria. This minimal model, a multispecies totally asymmetric exclusion process (TASEP) with directional switching, can provide a framework for understanding the interplay between the switching dynamics of individual particles and the collective movement of particles in one dimension. When switching is much faster than translocation, the steady-state density and current profiles of the particles are homogeneous in the bulk and are well described by mean-field (MF) theory, as determined by comparison to a Monte Carlo simulation. In this limit, we can map this model to the exactly solvable partially asymmetric exclusion-process (PASEP) model. Away from this fast switching regime the MF theory fails, although the average bulk density profile still remains homogeneous. We study the steady-state behavior as a function of the ratio of the translocation and net switching rates Q and find a unique first-order phase transition at a finite Q associated with a discontinuous change of the bulk density. When the switching rate is decreased further (keeping translocation rate fixed), the system approaches a jammed phase with a net current that tends to zero as J~1/Q. We numerically construct the phase diagram for finite Q.
authors: Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore 560080, India.
authors: Sudipto
authors: S
authors: Muhuri
authors: Lenin
authors: L
authors: Shagolsem
authors: Madan
authors: M
authors: Rao
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000502:physiology*; D003198:Computer Simulation; D006801:Humans; D008954:Models, Biological