title: Thermotropic 'two-stage' liquid crystalline equilibrium crystalline lipid phase separation in microsomal membranes.
abstract: The effect of temperature on native microsomal membrane vesicles isolated from Tetrahymena is investigated by wide angle X-ray diffraction. A 4.2 reflection, typical for lipids in the crystalline state, can be recorded in the temperature range between 0 degree C and 35 degrees C. Quantitative evaluation of this reflection reveals a broad thermotropic 'two-stage' liquid crystalline equilibrium crystalline lipid phase separation with a 'breakpoint' at approx. 18 degrees C. This 'breakpoint' coincides with the emergency of lipid-protein segregations in endomembranes of intact Tetrahymena cells as previously visualized by freeze-etch electron microscopy.
mesh_terms: D000818:Animals; D003460:Crystallization; D007425:Intracellular Membranes / Q000502:physiology* / Q000648:ultrastructure; D008433:Mathematics; D008563:Membrane Lipids / Q000502:physiology*; D008861:Microsomes / Q000502:physiology*; D008968:Molecular Conformation; D013696:Temperature; D013769:Tetrahymena pyriformis / Q000502:physiology*; D014961:X-Ray Diffraction
chemical_list: D008563:Membrane Lipids