Diffusion of Macromolecules across the Nuclear Pore Complex

TL;DR

This paper presents a mesoscopic model for protein transport through nuclear pore complexes, comparing gel and brush models, and finds that gel models better explain observed diffusion behaviors.

Contribution

A unified mesoscopic model that captures protein transport in NPCs, distinguishing between gel and brush models and analyzing their diffusion properties.

Findings

Gel model predicts higher diffusion coefficients than brush model.

Faster gel relaxation leads to increased diffusion.

Results favor the gel model as the likely mechanism.

Abstract

Nuclear pore complexes (NPCs) are very selective filters that monitor the transport between the cytoplasm and the nucleoplasm. Two models have been suggested for the plug of the NPC. They are (i) it is a reversible hydrogel or (ii) it is a polymer brush. We propose a mesoscopic model for the transport of a protein through the plug, that is general enough to cover both. The protein stretches the plug and creates a local deformation. The bubble so created (prtoein+deformation) executes random walk in the plug. We find that for faster relaxation of the gel, the diffusion of the bubble is greater. Further, on using parameters appropriate for the brush, we find that the diffusion coefficient is much lower. Hence the gel model seems to be more likely explanation for the workings of the plug.