title: Sub-resolution lipid domains exist in the plasma membrane and regulate protein diffusion and distribution.
abstract: Lipid microdomains are postulated to regulate many membrane-associated processes but have remained highly controversial. Here we provide the first direct evidence that the plasma membrane of intact, live cells is comprised of a sub-resolution mixture of approximately 76% ordered and 24% disordered lipid domains, which correspond to liquid-ordered and -disordered model membranes. These measurements were based on the unmixing of fluorescence lifetime decays (phasor analysis) obtained from environmentally sensitive membrane dyes that report the degree of lipid packing. Using the transmembrane protein Linker for Activation of T cells (LAT) as an example, we demonstrate that association with ordered domains retarded LAT diffusion and decreased clustering in meso-scaled protein domains as analysed by super-resolution microscopy. Our data therefore propose a membrane model in which the majority of the plasma membrane is covered by cholesterol-dependent, ordered lipid domains that contribute to the non-random distribution and diffusion of membrane constituents.
authors.affiliation: Centre for Vascular Research and Australian Centre for Nanomedicine, University of New South Wales, High Street, Sydney, New South Wales 2052, Australia.
authors.forename: Dylan M
authors.initials: DM
authors.lastname: Owen
authors.forename: David J
authors.initials: DJ
authors.lastname: Williamson
authors.forename: Astrid
authors.initials: A
authors.lastname: Magenau
authors.forename: Katharina
authors.initials: K
authors.lastname: Gaus
mesh_terms: D015081:2-Naphthylamine / Q000031:analogs & derivatives; D002462:Cell Membrane / Q000378:metabolism / Q000502:physiology*; D004058:Diffusion; D005456:Fluorescent Dyes; D006367:HeLa Cells; D006801:Humans; D007848:Laurates; D008563:Membrane Lipids / Q000378:metabolism / Q000502:physiology*; D021962:Membrane Microdomains / Q000378:metabolism / Q000502:physiology*; D008954:Models, Biological; D011506:Proteins / Q000378:metabolism*
chemical_list: D005456:Fluorescent Dyes; D007848:Laurates; D008563:Membrane Lipids; D011506:Proteins; D015081:2-Naphthylamine; C065580:laurdan