title: Membrane binding of a lipidated N-Ras protein studied in lipid monolayers.
abstract: The adsorption of doubly lipidated full-length N-Ras protein on 1,2-dipalmitoyl-sn-phosphatidylcholine (DPPC) monolayers was studied by lateral pressure analysis, grazing incidence X-ray diffraction (GIXD), and specular reflectivity (XR). N-Ras protein adsorbs to the DPPC monolayer (lateral pressure of 20 mN/m) from the subphase thereby increasing the lateral pressure in the monolayer by 4 mN/m. The protein insertion does not alter the tilt angle and structure of the lipid molecules at the air/water interface but influences the electron density profile of the monolayer. Further, electron density differences into the subphase were observed. The Fresnel normalized reflectivity could be reconstructed in the analysis using box models yielding electron density profiles of the DPPC monolayer in the absence and in the presence of N-Ras protein. The electron density profiles of the DPPC monolayer in the presence of Ras showed clear intensity variations in the headgroup/glycerol/upper chain region, the so-called interface region where previous bilayer studies had confirmed Ras binding.
authors.affiliation: Institute of Medical Physics and Biophysics, University of Leipzig, Leipzig, Germany. frank.bringezu@medizin.uni-leipzig.de
authors.forename: Frank
authors.initials: F
authors.lastname: Bringezu
authors.forename: Monika
authors.initials: M
authors.lastname: Majerowicz
authors.forename: Shaoying
authors.initials: S
authors.lastname: Wen
authors.forename: Guido
authors.initials: G
authors.lastname: Reuther
authors.forename: Kui-Thong
authors.initials: KT
authors.lastname: Tan
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kuhlmann
authors.forename: Herbert
authors.initials: H
authors.lastname: Waldmann
authors.forename: Daniel
authors.initials: D
authors.lastname: Huster
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D000327:Adsorption; D001665:Binding Sites; D008051:Lipid Bilayers / Q000737:chemistry*; D011485:Protein Binding; D012996:Solutions; D053835:Unilamellar Liposomes / Q000737:chemistry*; D018631:ras Proteins / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D012996:Solutions; D053835:Unilamellar Liposomes; D015060:1,2-Dipalmitoylphosphatidylcholine; D018631:ras Proteins