title: Critical points in charged membranes containing cholesterol.
abstract: Epifluorescence microscopy is used to determine phase diagrams for lipid monolayers containing binary mixtures of cholesterol or dihydrocholesterol and dimyristoylphosphatidylserine, as well as ternary mixtures that also contain ganglioside G(M1). The phase diagrams are unusual in that they show multiple critical points: two upper miscibility critical points and one lower miscibility critical point. These critical points all are associated with the formation of condensed complexes between these lipids and cholesterol (or dihydrocholesterol). The miscibility critical pressures depend on subphase pH and ionic strength. Changes in critical pressures due to changes in subphase composition are closely related to changes in membrane electrostatic pressure and surface ionization.
mesh_terms: D000818:Animals; D004083:Cholestanol / Q000737:chemistry; D002784:Cholesterol / Q000737:chemistry*; D005615:Freezing; D005677:G(M1) Ganglioside / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008563:Membrane Lipids / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D009994:Osmolar Concentration; D011312:Pressure; D012756:Sheep; D055672:Static Electricity; D013816:Thermodynamics; D014494:Unithiol / Q000737:chemistry
chemical_list: D008563:Membrane Lipids; D005677:G(M1) Ganglioside; D014494:Unithiol; D004083:Cholestanol; D002784:Cholesterol