Lateral diffusion of a protein on a fluctuating membraneE. Reister and U. Seifert
II. Institut für Theoretische Physik, Universität Stuttgart - 70550 Stuttgart, Germany
received 1 March 2005; accepted in final form 27 June 2005
published online 27 July 2005
Measurements of lateral diffusion of proteins in a membrane typically assume that the movement of the protein occurs in a flat plane. Real membranes, however, are subject to thermal fluctuations, leading to movement of an inclusion into the third dimension. We calculate the magnitude of this effect by projecting real three-dimensional diffusion onto an effective one on a flat plane. We consider both a protein that is free to diffuse in the membrane and one that also couples to the local curvature. For a freely diffusing inclusion the measured projected diffusion constant is up to 15% smaller than the actual value. Coupling to the curvature enhances diffusion significantly up to a factor of two.
87.15.Vv - Diffusion.
87.16.Dg - Membranes, bilayers, and vesicles.
05.40.-a - Fluctuation phenomena, random processes, noise, and Brownian motion.
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