Lateral diffusion in an archipelago. The effect of mobile obstacles

Area of Science:

• Biophysics
• Membrane Biology
• Computational Biology

Background:

• Lateral diffusion of membrane components (tracers) is crucial for cellular functions.
• Membrane proteins (obstacles) can impede tracer diffusion, especially at high concentrations.
• Percolation theory describes immobile obstacles, but mobile obstacles introduce further complexity.

Purpose of the Study:

• To investigate the effect of mobile protein obstacles on lateral diffusion in membranes.
• To quantify the relationship between obstacle concentration, relative jump rates, and diffusion constants.
• To compare computational findings with experimental data for membrane proteins.

Main Methods:

• Monte Carlo simulations were performed on square and triangular lattices.
• Calculations assessed diffusion constants based on varying obstacle concentrations and relative jump rates.
• The diffusion of particles of different sizes was also simulated.

Main Results:

• The diffusion constant of tracers is significantly reduced by mobile obstacles.
• Diffusion is dependent on both the area fraction of obstacles and their mobility relative to tracers.
• Simulated diffusion constants align with experimental observations for gramicidin and bacteriorhodopsin.

Conclusions:

• Mobile protein obstacles play a significant role in modulating membrane diffusion.
• Factors like protein-protein interactions and altered lipid viscosity also impact diffusion rates.
• Findings have implications for understanding protein diffusion in various cellular contexts.