Organization of membrane-associated proteins in lipid bilayers.

Lateral organization of proteins in biomembranes is vitally important to membrane functions such as signal transduction, endocytosis, and membrane trafficking. One of the major goals in current biomembrane science is to reveal the microscopic mechanism of membrane-associated protein organization in biomembranes. Here, we investigate the structural organization of membrane-associated proteins in lipid bilayers by combining self-consistent field theory with density functional theory. The present study can simultaneously take into account the entropy effect of lipids, depletion effect of membrane-associated proteins due to the presence of lipid headgroups as well as the effect of interfacial interaction. By varying the volume fraction of lipids, we examine various effects on protein organization, and reveal that a close-packed crystal structure appears at low lipid volume fractions due to interfacial energy and weak depletion effect, whereas a chain structure with branches occurs at high lipid volume fractions mainly due to strong depletion. The present results may provide some theoretical insight into further experiments on organization of membrane proteins.