Cholesterol transfer between lipid vesicles. Effect of phospholipids and gangliosides. 1988

P D Thomas, and M J Poznansky
Department of Physiology, University of Alberta, Edmonton, Canada.

The effect of lipid composition on the rate of cholesterol movement between cellular membranes is investigated using lipid vesicles. The separation of donor and acceptor vesicles required for rate measurement is achieved by differential centrifugation so that the lipid effect can be quantified in the absence of a charged lipid generally used for ion-exchange-based separation. The rate of cholesterol transfer from small unilamellar vesicles (SUVs) containing 50 mol% cholesterol to a common large unilamellar vesicle (LUV) acceptor containing 20 mol% cholesterol decreases with increasing mol% of sphingomyelin in the SUVs, while phosphatidylethanolamine and phosphatidylserine have no appreciable effect at physiologically relevant levels. There is a large decrease in rate when phosphatidylethanolamine constitutes 50 mol% of donor phospholipids. Interestingly, gangliosides which have the same hydrocarbon moiety as sphingomyelin exert an opposite effect. The effect of spingomyelin seems to be mediated by its ability to decrease the fluidity of the lipid matrix, while that of gangliosides may arise from a weakening of phosphatidylcholine-cholesterol interactions or from a more favourable (less polar) microenvironment for the desorption of cholesterol provided by the head-group interactions involving sugar residues. If the effect of asymmetric transbilayer distribution of lipids is taken into consideration, the observed composition-dependent rate changes could partly account for the large difference in the rates of cholesterol desorption from the inner and outer layers of plasma membrane. Such rate differences may be responsible for an unequal steady-state distribution of cholesterol among various cellular membranes and lipoproteins.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008055 Lipids A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed) Lipid
D008563 Membrane Lipids Lipids, predominantly phospholipids, cholesterol and small amounts of glycolipids found in membranes including cellular and intracellular membranes. These lipids may be arranged in bilayers in the membranes with integral proteins between the layers and peripheral proteins attached to the outside. Membrane lipids are required for active transport, several enzymatic activities and membrane formation. Cell Membrane Lipid,Cell Membrane Lipids,Membrane Lipid,Lipid, Cell Membrane,Lipid, Membrane,Lipids, Cell Membrane,Lipids, Membrane,Membrane Lipid, Cell,Membrane Lipids, Cell
D010743 Phospholipids Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system. Phosphatides,Phospholipid
D002784 Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Epicholesterol
D004912 Erythrocytes Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN. Blood Cells, Red,Blood Corpuscles, Red,Red Blood Cells,Red Blood Corpuscles,Blood Cell, Red,Blood Corpuscle, Red,Erythrocyte,Red Blood Cell,Red Blood Corpuscle
D005732 Gangliosides A subclass of ACIDIC GLYCOSPHINGOLIPIDS. They contain one or more sialic acid (N-ACETYLNEURAMINIC ACID) residues. Using the Svennerholm system of abbrevations, gangliosides are designated G for ganglioside, plus subscript M, D, or T for mono-, di-, or trisialo, respectively, the subscript letter being followed by a subscript arabic numeral to indicated sequence of migration in thin-layer chromatograms. (From Oxford Dictionary of Biochemistry and Molecular Biology, 1997) Ganglioside,Sialoglycosphingolipids
D006207 Half-Life The time it takes for a substance (drug, radioactive nuclide, or other) to lose half of its pharmacologic, physiologic, or radiologic activity. Halflife,Half Life,Half-Lifes,Halflifes
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001692 Biological Transport The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments. Transport, Biological,Biologic Transport,Transport, Biologic

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