Regensburg 2007 – scientific programme

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BP: Fachverband Biologische Physik

BP 26: Poster Session II

BP 26.42: Poster

Thursday, March 29, 2007, 17:00–19:30, Poster B

Diffusion control of proteins within model membrane systems — Florian Rückerl, Philipp Rauch, Josef Käs, and •Carsten Selle — University of Leipzig, Institute for Experimental Physics I, Linnestraße 5, 04103 Leipzig, Germany

Lateral diffusion within membranes plays a major role in biologically important processes as signal transduction.

Diffusion of proteins within inhomogeneous membranes was mimicked by motion of surface-charged fluorescent polystyrene beads in monolayers where two differently ordered phases coexist. Associated to ordered liquid-condensed (LC) domains, dimensionally reduced motion of the model proteins in the liquid-expanded (LE) phase was experimentally found which was caused by dipole-dipole interactions. Monte-Carlo simulations demonstrate that model protein diffusion can be strongly affected by the strength of these interactions and the domain size.

We also studied nanoparticles diffusing on the surface of giant unilamellar vesicles (GUVs) composed of either a single lipid or a mixture of lipids exhibiting fluid coexisting phases. The latter represents an even more similar mimic to cell membranes. The adhesion of the (charged) nanoparticles was found to depend on the surrounding medium.

It seems conceivable that living cells could control protein motion accomplished by similar mechanisms in order to enhance kinetics of bimolecular enzyme reactions occuring in the membrane.