A statistical mechanical theory for the adsorption of protein to liposomal membranes.

The observed topology change of spherical lipid vesicles to coffee cups [Saitoh, A. et al., Proc. Natl. Acad. Sci. USA 95 (1998) 1026] was analyzed by a statistical mechanical theory. The topology change was due to the adsorption of talin molecules to the orifices of the coffee cups. The adsorption isotherm of talin between an aqueous solution and the vesicle membrane was analyzed by taking account of the bending energy of the membrane. The equilibrium is determined by the balance of the energy gain for the adsorption of talin to the periphery of the vesicles and the change of the bending energy of the membrane due to the shape change. The observed coexistence of coffee cups and sheet-like vesicles were reproduced. Vesicles with two orifices were also analyzed and theoretically reproduced.