title: Spatial distribution and activity of Na(+)/K(+)-ATPase in lipid bilayer membranes with phase boundaries.
abstract: We have reconstituted functional Na(+)/K(+)-ATPase (NKA) into giant unilamellar vesicles (GUVs) of well-defined binary and ternary lipid composition including cholesterol. The activity of the membrane system can be turned on and off by ATP. The hydrolytic activity of NKA is found to depend on membrane phase, and the water relaxation in the membrane on the presence of NKA. By collapsing and fixating the GUVs onto a solid support and using high-resolution atomic-force microscopy (AFM) imaging we determine the protein orientation and spatial distribution at the single-molecule level and find that NKA is preferentially located at lo/ld interfaces in two-phase GUVs and homogeneously distributed in single-phase GUVs. When turned active, the membrane is found to unbind from the support suggesting that the protein function leads to softening of the membrane.
authors.affiliation: MEMPHYS - Center for Biomembrane Physics, University of Southern Denmark, DK-5230 Odense M, Denmark; Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, DK-5230 Odense M, Denmark; Max Planck Institute of Colloids and Interfaces, Department of Theory and Bio-Systems, Science Park Golm, 14476 Potsdam, Germany. Electronic address: Tripta.Bhatia@mpikg.mpg.de.
authors.forename: Tripta
authors.initials: T
authors.lastname: Bhatia
authors.affiliation: Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: Flemming
authors.initials: F
authors.lastname: Cornelius
authors.affiliation: MEMPHYS - Center for Biomembrane Physics, University of Southern Denmark, DK-5230 Odense M, Denmark; Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Brewer
authors.affiliation: MEMPHYS - Center for Biomembrane Physics, University of Southern Denmark, DK-5230 Odense M, Denmark; Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Bagatolli
authors.affiliation: MEMPHYS - Center for Biomembrane Physics, University of Southern Denmark, DK-5230 Odense M, Denmark; Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, DK-5230 Odense M, Denmark.
authors.forename: Adam C
authors.initials: AC
authors.lastname: Simonsen
authors.affiliation: MEMPHYS - Center for Biomembrane Physics, University of Southern Denmark, DK-5230 Odense M, Denmark; Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, DK-5230 Odense M, Denmark.
authors.forename: John H
authors.initials: JH
authors.lastname: Ipsen
authors.affiliation: MEMPHYS - Center for Biomembrane Physics, University of Southern Denmark, DK-5230 Odense M, Denmark; Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, DK-5230 Odense M, Denmark.
authors.forename: Ole G
authors.initials: OG
authors.lastname: Mouritsen
mesh_terms: D008051:Lipid Bilayers; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry*; D053835:Unilamellar Liposomes
chemical_list: D008051:Lipid Bilayers; D053835:Unilamellar Liposomes; D000254:Sodium-Potassium-Exchanging ATPase
keywords: Domains; Giant unilamellar vesicles; Membrane biophysics; Membrane protein; Membranes; Na(+)/K(+)-ATPase; Protein–lipid interaction