Run-and-pause dynamics of cytoskeletal motor proteins

TL;DR

This paper develops an analytical model for cytoskeletal motor proteins that alternate between active motion and pause phases, revealing complex diffusive behaviors influenced by environmental conditions and transition rates.

Contribution

It introduces a comprehensive model capturing the effects of transition asymmetry, network structure, and initial conditions on motor protein dynamics.

Findings

Multiple anomalous diffusive regimes identified

Crossover times vary by several orders of magnitude

Phase diagrams map the influence of transition rates

Abstract

Cytoskeletal motor proteins are involved in major intracellular transport processes which are vital for maintaining appropriate cellular function. The motor exhibits distinct states of motility: active motion along filaments, and effectively stationary phase in which it detaches from the filaments and performs passive diffusion in the vicinity of the detachment point due to cytoplasmic crowding. The transition rates between motion and pause phases are asymmetric in general, and considerably affected by changes in environmental conditions which influences the efficiency of cargo delivery to specific targets. By considering the motion of molecular motor on a single filament as well as a dynamic filamentous network, we present an analytical model for the dynamics of self-propelled particles which undergo frequent pause phases. The interplay between motor processivity, structural properties of filamentous network, and transition rates between the two states of motility drastically changes the dynamics: multiple transitions between different types of anomalous diffusive dynamics occur and the crossover time to the asymptotic diffusive or ballistic motion varies by several orders of magnitude. We map out the phase diagrams in the space of transition rates, and address the role of initial conditions of motion on the resulting dynamics.