Regensburg 2010 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 19: Membranes and Vesicles

BP 19.9: Vortrag

Mittwoch, 24. März 2010, 12:15–12:30, H43

Diffusing proteins on a fluctuating membrane: Analytical theory and simulations — •Ellen Reister, Stefan M. Leitenberger, and Udo Seifert — II. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart

Using both analytical calculations and computer simulations we consider the lateral diffusion of a membrane protein and the fluctuation spectrum of the membrane in which the protein is embedded. The membrane protein interacts with the membrane shape through its spontaneous curvature and bending rigidity. Using a rigorous path-integral approach we derive an analytical expression for the effective lateral diffusion coefficient of the protein in the limit of small ratios of temperature and bending rigidity, which is the biologically relevant limit. Simulation results show good quantitative agreement with our analytical result. The analysis of the correlation functions contributing to the diffusion coefficient reveals that correlations between the stochastic force of the protein and the response in the membrane shape are responsible for the reduction of the diffusion coefficient.

Our quantitative analysis of the membrane height correlation spectrum shows a non negligible influence of the protein-membrane interaction causing a distinctly altered wave-vector dependence compared to a free membrane. Furthermore, the time correlations exhibit the two relevant timescales of the system: that of membrane fluctuations and that of protein diffusion that is typically much longer than the other. We suggest that the long-time decay of height correlations may provide a means to determine effective diffusion coefficients of proteins.