Transport by molecular motors in the presence of static defects

TL;DR

This paper models molecular motor transport along filaments with static defects, revealing how different defect types impact motor velocity, run length, and cargo transport efficiency.

Contribution

It introduces a theoretical framework distinguishing three defect types and analyzes their distinct effects on motor transport properties.

Findings

Stepping and unbinding defects significantly reduce motor velocity and run length.

Binding defects have a smaller impact on single motor transport.

Binding defects strongly affect cargo transport by motor teams.

Abstract

The transport by molecular motors along cytoskeletal filaments is studied theoretically in the presence of static defects. The movements of single motors are described as biased random walks along the filament as well as binding to and unbinding from the filament. Three basic types of defects are distinguished, which differ from normal filament sites only in one of the motors' transition probabilities. Both stepping defects with a reduced probability for forward steps and unbinding defects with an increased probability for motor unbinding strongly reduce the velocities and the run lengths of the motors with increasing defect density. For transport by single motors, binding defects with a reduced probability for motor binding have a relatively small effect on the transport properties. For cargo transport by motors teams, binding defects also change the effective unbinding rate of the cargo particles and are expected to have a stronger effect.