Bottleneck-induced transitions in a minimal model for intracellular transport

We consider the influence of disorder on the nonequilibrium steady
state of a minimal model for intracellular transport. In this model
particles move unidirectionally according to the totally asymmetric
exclusion process (TASEP) and are coupled to a bulk reservoir by
Langmuir kinetics. Our discussion focuses on localized point
defects acting as a bottleneck for the particle transport.
Combining analytic methods and numerical simulations, we identify a
rich phase behavior as a function of the defect strength. Our
analytical approach relies on an effective mean-field theory
obtained by splitting the lattice into two subsystems, which are
effectively connected exploiting the local current conservation.
Introducing the key concept of a carrying capacity, the maximal
current that can flow through the bulk of the system (including the
defect), we discriminate between the cases where the defect is
irrelevant and those where it acts as a bottleneck and induces
various novel phases (called bottleneck phases). Contrary to the
simple TASEP in the presence of inhomogeneities, many scenarios
emerge and translate into rich underlying phase diagrams, the
topological properties of which are discussed.