Lateral diffusion of a protein on a fluctuating membrane

TL;DR

This paper investigates how thermal fluctuations and curvature coupling in membranes affect the measured lateral diffusion of proteins, revealing that fluctuations can reduce observed diffusion by up to 15%, while curvature coupling can enhance it up to twofold.

Contribution

It provides a quantitative analysis of how membrane fluctuations and curvature coupling influence the effective diffusion measurements of membrane proteins.

Findings

Projected diffusion constant can be up to 15% smaller due to fluctuations.

Curvature coupling can increase diffusion by up to a factor of two.

Thermal fluctuations significantly impact diffusion measurements.

Abstract

Measurements of lateral diffusion of proteins in a membrane typically assume that the movement of the protein occurs in a flat plane. Real membranes, however, are subject to thermal fluctuations, leading to movement of an inclusion into the third dimension. We calculate the magnitude of this effect by projecting real three-dimensional diffusion onto an effective one on a flat plane. We consider both a protein that is free to diffuse in the membrane and one that also couples to the local curvature. For a freely diffusing inclusion the measured projected diffusion constant is up to 15% smaller than the actual value. Coupling to the curvature enhances diffusion significantly up to a factor of two.