Theory of self-assembly of microtubules and motors

TL;DR

This paper develops a theoretical model for the organization of microtubules and molecular motors, explaining how their interactions lead to structures like vortices and asters observed in experiments.

Contribution

It introduces a new model derived from microscopic interactions, linking motor-filament dynamics to large-scale pattern formation in microtubule arrays.

Findings

Orientational instability occurs at high filament and motor densities.

Vortex and aster formations are explained by the model.

Interaction kernel derived from microscopic filament-motor interactions.

Abstract

We derive a model describing spatio-temporal organization of an array of microtubules interacting via molecular motors. Starting from a stochastic model of inelastic polar rods with a generic anisotropic interaction kernel we obtain a set of equations for the local rods concentration and orientation. At large enough mean density of rods and concentration of motors, the model describes an orientational instability. We demonstrate that the orientational instability leads to the formation of vortices and (for large density and/or kernel anisotropy) asters seen in recent experiments. We derive the specific form of the interaction kernel from the detailed analysis of microscopic interaction of two filaments mediated by a moving molecular motor, and extend our results to include variable motor density and motor attachment to the substrate.