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The eukaryotic cell membrane is connected to a dense actin rich cortex. We present FCS and STED experiments showing that dense membrane bound actin networks have severe influence on lipid phase separation. A minimal actin cortex was bound to a supported lipid bilayer via biotinylated lipid streptavidin complexes (pinning sites). In general, actin binding to ternary membranes prevented macroscopic liquid-ordered and liquid-disordered domain formation, even at low temperature. Instead, depending on the type of pinning lipid, an actin correlated multi-domain pattern was observed. FCS measurements revealed hindered diffusion of lipids in the presence of an actin network. To explain our experimental findings, a new simulation model is proposed, in which the membrane composition, the membrane curvature, and the actin pinning sites are all coupled. Our results reveal a mechanism how cells may prevent macroscopic demixing of their membrane components, while at the same time regulate the local membrane composition. DOI: http://dx.doi.org/10.7554/eLife.01671.001.

Original publication

DOI

10.7554/eLife.01671

Type

Journal article

Journal

Elife

Publication Date

18/03/2014

Volume

3

Keywords

STED microscopy, cortical actin, fluorescence correlation spectroscopy, lipid phase separation, membrane organization, pinning sites, Actins, Computer Simulation, Lipid Metabolism, Membranes, Microscopy, Fluorescence, Models, Theoretical, Protein Binding