title: Atomic force microscopy imaging of Xenopus laevis oocyte plasma membrane purified by ultracentrifugation.
abstract: Atomic force microscopy (AFM) was used to investigate the native plasma membrane of Xenopus laevis (X. laevis) oocyte purified by means of ultracentrifugation on sucrose gradient and subsequently adsorbed on mica leaves through a physisorption process. Reproducible AFM topography images were collected, analyzed, and compared. AFM images showed the presence of large single or double bilayer membrane sheets covered with protein complexes. The lateral dimension and height of protein complexes imaged in air showed a normal distribution centred on 15.4 +/- 0.4 nm (mean +/- SE; n = 59) and 3.9 +/- 0.2 nm (mean +/- SE; n = 57), respectively. A density of about 270 protein complexes per square micron was calculated. Less frequently, ordered nanometer domains with densely packed protein complexes arranged in hexagonal patterns were also visualized in AFM images, confirming previously published data. Their lateral dimension and height showed a normal distribution centred on 23.0 +/- 0.4 nm (mean +/- SE; n = 42) and 1.5 +/- 0.6 nm (mean +/- SE; n = 90), respectively. A density of about 870 protein complexes per square micrometer was calculated. Advantages and drawbacks of this new sample preparation for AFM imaging are discussed.
authors.affiliation: Giovanni Esposito Institute of General Physiology and Biological Chemistry, University of Milan, Via Trentacoste 2, Milan, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Santacroce
authors.forename: Francesco
authors.initials: F
authors.lastname: Orsini
authors.forename: Stefania Anna
authors.initials: SA
authors.lastname: Mari
authors.forename: Massimo
authors.initials: M
authors.lastname: Marinone
authors.forename: Cristina
authors.initials: C
authors.lastname: Lenardi
authors.forename: Sara
authors.initials: S
authors.lastname: Bettè
authors.forename: Vellea Franca
authors.initials: VF
authors.lastname: Sacchi
authors.forename: Giulio
authors.initials: G
authors.lastname: Poletti
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure*; D002499:Centrifugation, Density Gradient; D005260:Female; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D018625:Microscopy, Atomic Force; D009865:Oocytes / Q000648:ultrastructure*; D014982:Xenopus laevis
chemical_list: D008051:Lipid Bilayers; D046911:Macromolecular Substances