Activity of Transmembrane Proteins Induces Magnification of Shape Fluctuations of Lipid Membranes

We report the first experimental evidence of the effect of the activity of transmembrane proteins on shape fluctuations of a lipid membrane. We incorporate a light-driven proton pump, the bacteriorhodopsin (BR), inside the phospholipid bilayer of fluctuating giant vesicles. Using the micropipet technique, we measure the excess surface area due to the fluctuations of the vesicles. The excess surface area is larger when the BR pumps protons than when it is not activated.