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BP: Fachverband Biologische Physik
BP 21: Membranes and Vesicles II
BP 21.4: Vortrag
Dienstag, 1. April 2014, 14:45–15:00, ZEU 250
Domain formation in a membrane coupled to an actin network — •Sina Sadeghi1, Alf Honigmann2, Christian Eggeling2, and Richard Vink1 — 1Institute of Theoretical Physics, Georg-August-Universität Göttingen, Göttingen, Germany — 2Max Planck Institute for Biophysical Chemistry, Department of NanoBiophotonics, Göttingen, Germany
Lateral heterogeneity of the plasma membrane is receiving much attention. In contrast to model membranes which exhibit phase separation below a certain temperature, biological membranes typically do not phase separate. One hypothesis is that the cytoskeleton network on the cytoplasmic side of the cell membrane prevents phase separation. This motivates the study of pattern formation in membranes in the presence of an actin network. To this end, a series of experiments were performed on a supported membrane that was bound to an actin network via certain cross linker lipids (pinning sites). These experiments show that the lipid domain pattern that arises is strongly affected by the interaction of the pinning site with the surrounding diffusing lipids. In the present work, we propose an extended (Ising) model to rationalize these findings. Our model includes the effects of the membrane curvature on the lipid organization. To be precise, we modelled the elastic properties of the membrane using the Helfrich expansion, and assumed a coupling between the lipid domains and the local membrane curvature. Using computer simulation, we find that this coupling is crucial in order to reproduce the experimental results, especially for the case where the pinning sites have a small affinity for saturated lipids.