Berlin 2008 – scientific programme
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BP: Fachverband Biologische Physik
BP 27: Membrane Morphology and Adhesion
BP 27.4: Talk
Friday, February 29, 2008, 11:15–11:30, C 243
Large scale organization in crowded membranes — •Stefan Semrau1, Timon Idema2, Cornelis Storm2, and Thomas Schmidt1 — 1Physics of Life Processes, Leiden University, The Netherlands — 2Lorentz Institute for Theoretical Physics, Leiden University, The Netherlands
Over the past years, the classical fluid mosaic model - in which membrane proteins have ample space to explore the entire membrane - has undergone some serious revision. In actuality, the membrane environment is highly crowded and heterogeneous. Crowding has profound implications for the dynamical behavior of the proteins, and is therefore a determining factor for the mechanisms of cell signaling. Only very recently the importance of membrane mediated interactions in such processes was recognized. Here we use two-phase GUVs (giant unilamellar vesicles) with multiple budded, liquid ordered domains to model this class of interactions. Such budded domains repel as our recent analytical model of completely phase separated GUVs (Semrau, Idema et al.) suggests. Here we measure the strength of the repulsion by analysis of domain diffusion and find that it gives rise to a preferred domain size. Furthermore, we observe that the interaction strength has peaks at distinct domain sizes. These sizes correspond to the addition of a domain to a shell of domains surrounding a central, pinned domain. This implies that in a crowded system governed by membrane mediated interactions clustering of proteins of similar size or interaction strength is promoted.