Lateral depletion effect on two-dimensional ordering of bacteriorhodopsins in a lipid bilayer: A theoretical study based on a binary hard-disk model

TL;DR

This theoretical study uses a binary hard-disk model to analyze how lateral depletion influences the two-dimensional ordering of bacteriorhodopsins in lipid bilayers, highlighting the depletion effect's role in protein association.

Contribution

It introduces a phase diagram approach considering depletion effects, providing insights into protein ordering and critical concentrations in lipid bilayers.

Findings

Critical concentration ratios match experimental data when lipid interactions are included.

Depletion effects significantly influence transmembrane protein association.

Phase diagrams elucidate the ordering behavior of bacteriorhodopsins.

Abstract

The two-dimensional ordering of bacteriorhodopsins in a lipid bilayer was studied using a binary hard-disk model. The phase diagrams were calculated, taking into account the lateral depletion effects. The critical concentrations of the protein ordering for the monomers and the trimers were obtained from the phase diagrams. The critical concentration ratio agreed well with the experiment when the repulsive core interaction between the depletants, namely the lipids, was taken into account. The results suggest that the depletion effect plays an important role in the association behaviors of transmembrane proteins.