Interactions of clathrin coat with model lipid membranes.

The interaction of coat proteins from coated vesicles with model lipid membranes was examined using small unilamellar vesicles of dipalmitoylglycerophosphocholine as model membranes. Changes in membrane permeability were measured by the leakage of entrapped fluorescent dye, carboxyfluorescein. Both clathrin and the 55000-Da protein were found to be active. Density gradient centrifugation showed the formation of an irreversible protein-lipid complex. Dynamic light-scattering measurements showed that this complex is significantly larger than the original vesicles, suggesting that fusion is induced. The effects of pH, urea, Tris and ionic strength were studied and the possible biological relevance of the results is discussed.