title: The structure of complexes between phosphatidylethanolamine and glucosylceramide: a matrix for membrane rafts.
abstract: Interaction between membrane lipids creates lateral domains within which essential membrane processes like trans-membrane signaling, differentiation etc. take place. Attention has focused on liquid-ordered phases formed by sphingomyelin and cholesterol but formation of ordered domains on the cytoplasmic membrane surfaces has largely been neglected. Synchrotron X-ray powder diffraction methods were used to investigate the interaction between two components of the cytoplasmic leaflet of the plasma membrane, phosphatidylethanolamine and glucosylceramide. Multilamellar dispersions of binary mixtures of different molecular species of phosphatidylethanolamine and glucosylceramide were examined. Stoichiometric complexes are formed when the phosphatidylethanolamine has at least one unsaturated fatty acid. The stoichiometry of the complexes was 2.0 fluid phospholipids per glucosylceramide with C22/24 N-acyl chains and 1.8 with C-12 chains. Saturated molecular species of phosphatidylethanolamines were immiscible with glucosylceramide. The complexes formed with unsaturated phosphatidylethanolamines and glucosylceramide are stable above physiological temperatures. A putative role of these matrices in membrane rafts is considered.
authors.affiliation: Department of Biochemistry, King's College London, London, UK. p.quinn@kcl.ac.uk
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Quinn
mesh_terms: D005963:Glucosylceramides / Q000737:chemistry*; D008051:Lipid Bilayers; D008567:Membranes, Artificial; D015394:Molecular Structure; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D005963:Glucosylceramides; D008051:Lipid Bilayers; D008567:Membranes, Artificial; D010714:Phosphatidylethanolamines; C483858:phosphatidylethanolamine