title: GPI-anchored proteins do not reside in ordered domains in the live cell plasma membrane.
abstract: The organization of proteins and lipids in the plasma membrane has been the subject of a long-lasting debate. Membrane rafts of higher lipid chain order were proposed to mediate protein interactions, but have thus far not been directly observed. Here we use protein micropatterning combined with single-molecule tracking to put current models to the test: we rearranged lipid-anchored raft proteins (glycosylphosphatidylinositol(GPI)-anchored-mGFP) directly in the live cell plasma membrane and measured the effect on the local membrane environment. Intriguingly, this treatment does neither nucleate the formation of an ordered membrane phase nor result in any enrichment of nanoscopic-ordered domains within the micropatterned regions. In contrast, we find that immobilized mGFP-GPIs behave as inert obstacles to the diffusion of other membrane constituents without influencing their membrane environment over distances beyond their physical size. Our results indicate that phase partitioning is not a fundamental element of protein organization in the plasma membrane.
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria.
authors.forename: Eva
authors.initials: E
authors.lastname: Sevcsik
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria.
authors.forename: Mario
authors.initials: M
authors.lastname: Brameshuber
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Fölser
authors.affiliation: School of Engineering and Environmental Sciences, University of Applied Sciences Upper Austria, Stelzhamerstrasse 23, Wels 4600, Austria.
authors.forename: Julian
authors.initials: J
authors.lastname: Weghuber
authors.affiliation: Department of NanoBiophotonics, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany.
authors.forename: Alf
authors.initials: A
authors.lastname: Honigmann
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, Vienna 1040, Austria.
authors.forename: Gerhard J
authors.initials: GJ
authors.lastname: Schütz
mesh_terms: D018957:CD59 Antigens / Q000737:chemistry / Q000378:metabolism; D002277:Carcinoma / Q000378:metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D017261:Glycosylphosphatidylinositols / Q000737:chemistry / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D006801:Humans; D007140:Immunoglobulin Fab Fragments; D058635:Lipid-Linked Proteins / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary
chemical_list: D018957:CD59 Antigens; D017261:Glycosylphosphatidylinositols; D007140:Immunoglobulin Fab Fragments; D058635:Lipid-Linked Proteins; D049452:Green Fluorescent Proteins