Modelling cytoskeletal traffic: an interplay between passive diffusion and active transport

TL;DR

This paper models motor protein transport on the cytoskeleton using a network-based TASEP-LK model, revealing how different exchange rates lead to distinct heterogeneity regimes and a unified understanding of transport dynamics.

Contribution

It introduces a network TASEP-LK model for cytoskeletal transport and develops an effective rate diagram approach to analyze different heterogeneity regimes.

Findings

Identification of three steady-state regimes based on exchange rates.

Development of effective rate diagrams for network analysis.

Demonstration of how local and global heterogeneities emerge in different regimes.

Abstract

We introduce the totally asymmetric exclusion process with Langmuir kinetics (TASEP-LK) on a network as a microscopic model for active motor protein transport on the cytoskeleton, immersed in the diffusive cytoplasm. We discuss how the interplay between active transport along a network and infinite diffusion in a bulk reservoir leads to a heterogeneous matter distribution on various scales. We find three regimes for steady state transport, corresponding to the scale of the network, of individual segments or local to sites. At low exchange rates strong density heterogeneities develop between different segments in the network. In this regime one has to consider the topological complexity of the whole network to describe transport. In contrast, at moderate exchange rates the transport through the network decouples, and the physics is determined by single segments and the local topology. At last, for very high exchange rates the homogeneous Langmuir process dominates the stationary state. We introduce effective rate diagrams for the network to identify these different regimes. Based on this method we develop an intuitive but generic picture of how the stationary state of excluded volume processes on complex networks can be understood in terms of the single-segment phase diagram.