title: Existence of a flat phase in red cell membrane skeletons.
abstract: Biomolecular membranes display rich statistical mechanical behavior. They are classified as liquid in the absence of shear elasticity in the plane of the membrane and tethered (solid) when the neighboring molecules or subunits are connected and the membranes exhibit solid-like elastic behavior in the plane of the membrane. The spectrin skeleton of red blood cells was studied as a model tethered membrane. The static structure factor of the skeletons, measured by small-angle x-ray and light scattering, was fitted with a structure factor predicted with a model calculation. The model describes tethered membrane sheets with free edges in a flat phase, which is a locally rough but globally flat membrane configuration. The fit was good for large scattering vectors. The membrane roughness exponent, zeta, defined through h alpha L zeta, where h is the average amplitude of out-of-plane fluctuations and L is the linear membrane dimension, was determined to be 0.65 +/- 0.10. Computer simulations of model red blood cell skeletons also showed this flat phase. The value for the roughness exponent, which was determined from the scaling properties of membranes of different sizes, was consistent with that from the experiments.
authors.affiliation: Department of Cellular and Developmental Biology, Harvard University, Cambridge, MA 02138.
authors.forename: C F
authors.initials: CF
authors.lastname: Schmidt
authors.forename: K
authors.initials: K
authors.lastname: Svoboda
authors.forename: N
authors.initials: N
authors.lastname: Lei
authors.forename: I B
authors.initials: IB
authors.lastname: Petsche
authors.forename: L E
authors.initials: LE
authors.lastname: Berman
authors.forename: C R
authors.initials: CR
authors.lastname: Safinya
authors.forename: G S
authors.initials: GS
authors.lastname: Grest
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003198:Computer Simulation; D004563:Electrochemistry; D004910:Erythrocyte Membrane / Q000737:chemistry / Q000648:ultrastructure*; D008027:Light; D008433:Mathematics; D008958:Models, Molecular; D012542:Scattering, Radiation; D013049:Spectrin / Q000737:chemistry / Q000648:ultrastructure*; D014965:X-Rays
chemical_list: D013049:Spectrin