Quantifying protein diffusion and capture on filaments

TL;DR

This paper develops a quantitative theory for protein diffusion and capture on filaments, showing how proteins localize at filament ends and enhance enzymatic reaction rates, surpassing traditional diffusion limits.

Contribution

It introduces a novel theoretical framework for diffusion and capture on filaments, highlighting the efficiency of end-association in protein localization and reaction acceleration.

Findings

End-association after 1D diffusion is key for tip-localization.

Diffusion and capture significantly increase enzymatic reaction velocity.

The process exceeds the three-dimensional diffusion limit for protein-filament end association.

Abstract

The functional relevance of regulating proteins is often limited to specific binding sites such as the ends of microtubules or actin-filaments. A localization of proteins on these functional sites is of great importance. We present a quantitative theory for a diffusion and capture process, where proteins diffuse on a filament and stop diffusing when reaching the filament's end. It is found that end-association after one-dimensional diffusion is the main source for tip-localization of such proteins. As a consequence, diffusion and capture is highly efficient in enhancing the reaction velocity of enzymatic reactions, where proteins and filament ends are to each other as enzyme and substrate. We show that the reaction velocity can effectively be described within a Michaelis-Menten framework. Together one-dimensional diffusion and capture beats the (three-dimensional) Smoluchowski diffusion limit for the rate of protein association to filament ends.