Long Range Protein-Protein Interaction in Membranes

A model of mechanical long range protein-protein interaction in membranes is proposed: a membrane bound protein may induce a distortion of the average lipid orientation which may then be transmitted by the lipid orientational elasticity orer · 1ong distances to a second protein.· The .elastic force field thus \u27 cre\u27ated may lead to both attractive and \u27 repulsive forces between the proteins. This type of interaction· is a special case of the mechanical long range forces between disclination in ordered fluids. The close analogy between the lipid mediated protein-protein interaction in membranes and the attraction between disclination lines in a nematic layer is illustrated. The long range interaction between membrane bound macromolecules may be important for the formation of enzyme complexes in biological membranes. A further pathway of enzyme- complex formation in biological membranes is the condensation of the proteins in small lipid domains that are formed upon thermalor a charge-induced phase separation in the lipid bilayer. It is shown that the charge induced domain formation may also provide a simple mechanism of transverse protein-protein coupling accross the membrane