title: Mechanical Properties of Nanoscopic Lipid Domains.
abstract: The lipid raft hypothesis presents insights into how the cell membrane organizes proteins and lipids to accomplish its many vital functions. Yet basic questions remain about the physical mechanisms that lead to the formation, stability, and size of lipid rafts. As a result, much interest has been generated in the study of systems that contain similar lateral heterogeneities, or domains. In the current work we present an experimental approach that is capable of isolating the bending moduli of lipid domains. This is accomplished using neutron scattering and its unique sensitivity to the isotopes of hydrogen. Combining contrast matching approaches with inelastic neutron scattering, we isolate the bending modulus of ∼13 nm diameter domains residing in 60 nm unilamellar vesicles, whose lipid composition mimics the mammalian plasma membrane outer leaflet. Importantly, the bending modulus of the nanoscopic domains differs from the modulus of the continuous phase surrounding them. From additional structural measurements and all-atom simulations, we also determine that nanoscopic domains are in-register across the bilayer leaflets. Taken together, these results inform a number of theoretical models of domain/raft formation and highlight the fact that mismatches in bending modulus must be accounted for when explaining the emergence of lateral heterogeneities in lipid systems and biological membranes.
authors.affiliation: Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.|Department of Physics and Astronomy, University of Tennessee , Knoxville, Tennessee 37996, United States.|Joint Institute for Neutron Sciences , Oak Ridge, Tennessee 37831, United States.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Nickels
authors.affiliation: Center for Molecular Biophysics, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.|Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996, United States.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Cheng
authors.affiliation: Center for Molecular Biophysics, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Barmak
authors.initials: B
authors.lastname: Mostofian
authors.affiliation: Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Stanley
authors.affiliation: Center for Molecular Biophysics, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Lindner
authors.affiliation: Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.|Joint Institute for Neutron Sciences , Oak Ridge, Tennessee 37831, United States.
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Heberle
authors.affiliation: Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.|Joint Institute for Neutron Sciences , Oak Ridge, Tennessee 37831, United States.
authors.forename: Stefania
authors.initials: S
authors.lastname: Perticaroli
authors.affiliation: Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Feygenson
authors.affiliation: Joint Institute for Neutron Sciences , Oak Ridge, Tennessee 37831, United States.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Egami
authors.affiliation: Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.|Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996, United States.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Standaert
authors.affiliation: Center for Molecular Biophysics, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.|Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee , Knoxville, Tennessee 37996, United States.
authors.forename: Jeremy C
authors.initials: JC
authors.lastname: Smith
authors.affiliation: Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Dean A A
authors.initials: DA
authors.lastname: Myles
authors.affiliation: Jülich Center for Neutron Science , Oak Ridge, Tennessee 37831, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Ohl
authors.affiliation: Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.|Department of Physics and Astronomy, University of Tennessee , Knoxville, Tennessee 37996, United States.|Joint Institute for Neutron Sciences , Oak Ridge, Tennessee 37831, United States.
authors.forename: John
authors.initials: J
authors.lastname: Katsaras
mesh_terms: D021962:Membrane Microdomains; D049329:Nanostructures