Lipid-mediated protein interaction in membranes.

This study describes the effects ensuing from a non-specific interaction between membrane integral proteins and the surrounding lipids. The results are obtained using an appropriate molecular field theory to describe the ordering of membrane lipids. The modification of the lipid structure near a protein molecule, while most pronounced within the annulus of the first neighbour molecules, extends two or three layers beyond the annulus. The ordering of lipids within the annulus has a modified temperature dependence, and becomes a continuous function of temperature for low lipid/protein ratios. The change in order of lipid molecules surrounding a protein leads to an indirect, lipid-mediated interaction between membrane integral proteins. This interaction depends sensitively on the bulk lipid order. Under favourable circumstances, it gives rise to protein aggregation.