Predicting the Directional Transport of Multivalent Cargo from Position Dependent Binding and Unbinding Rates

TL;DR

This paper introduces a general analytical model for predicting the movement of multivalent cargo based on position-dependent binding and unbinding rates, capturing effective diffusivity and directional velocity without additional parameters.

Contribution

The authors develop a novel analytical model that describes multivalent cargo transport driven by spatial variations in binding dynamics, applicable in one and two dimensions.

Findings

Model accurately reproduces experimental data

Predicts cargo velocity increases with binding rate and decreases with unbinding rate

Effective diffusivity and velocity depend on local binding/unbinding rates

Abstract

Multivalent cargo that can interact with substrates via multiple interaction sites exhibit shared characteristics despite being found in different systems at different length-scales. Here, a general analytical model has been developed that can describe the motion of multivalent cargo as a response to position dependence in the binding and unbinding rates of their interaction sites. Cargo exhibit both an effective diffusivity and velocity, which acts in the direction of increasing cargo-substrate binding rate and decreasing cargo-substrate unbinding rate. This model can reproduce previously published experimental findings using only the binding and unbinding rate distributions of cargo interaction sites, and without any further parameter fitting. Extension of the cargo binding model to two dimensions reveals an effective velocity with the same properties as that derived for the $1$D case.