title: A lipid bound actin meshwork organizes liquid phase separation in model membranes.
abstract: 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.
authors.affiliation: Department of NanoBiophotonics, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany.
authors.forename: Alf
authors.initials: A
authors.lastname: Honigmann
authors.forename: Sina
authors.initials: S
authors.lastname: Sadeghi
authors.forename: Jan
authors.initials: J
authors.lastname: Keller
authors.forename: Stefan W
authors.initials: SW
authors.lastname: Hell
authors.forename: Christian
authors.initials: C
authors.lastname: Eggeling
authors.forename: Richard
authors.initials: R
authors.lastname: Vink
mesh_terms: D000199:Actins / Q000378:metabolism*; D003198:Computer Simulation; D050356:Lipid Metabolism; D008566:Membranes / Q000737:chemistry* / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008962:Models, Theoretical; D011485:Protein Binding
chemical_list: D000199:Actins
keywords: STED microscopy; cortical actin; fluorescence correlation spectroscopy; lipid phase separation; membrane organization; pinning sites