Lipid Transfer Reactions: Fluorescence Studies
In cells the transport of lipid molecules from sources of biosynthesis or ingestion to the various membranes and organelles represents an important component of metabolism (Pagano and Sleight, 1985). The analogous problems of protein synthesis, membrane assembly, turnover, and secretion are also being actively studied by cell biologists. The important sites of lipid trafficking include the plasma compartment of blood and the cells of the vascular and extravascular compartment. The lipid composition of these sites includes cholesterol, cholesteryl esters, triglycerides, fatty acids, and phospholipids. Figure 1 schematically illustrates several pathways of lipid transfer in a membrane; these include lateral diffusion of the lipid in the membrane plane, spontaneous desorption into the surrounding aqueous compartment with subsequent uptake by an adjacent membrane surface, and bilayer translocation, which is commonly referred to as flip-flop. This latter mechanism is often accelerated by enzymes termed “translocases”. Other lipid transfer mechanisms not pictured include transient collisional complexes of lipid surfaces with lipid exchange occurring at the contact point, protein mediated transfer between lipid surfaces involving specific lipid-carrier proteins (e. g., phospholipid exchange protein), enzymatic degradation of lipid molecules and subsequent release of soluble lipid fragments from the membrane, and finally, transport of large lipid aggregates, such as lipoproteins, across the cell membrane via endocytosis.
KeywordsHigh Density Lipoprotein Aqueous Diffusion Elsevier Publishing Company Lipid Analog Spontaneous Transfer
Unable to display preview. Download preview PDF.
- Aniansson, E.A.G., Wall, S. N., Almgren, M., Hoffmann, H., Kielmann, I., Ulbricht, W., Zana, R., Lang, J., and Tondre, 1976, Theory of the Kinetics of Micellar Equilibria and Quantitative Interpretation of Chemical Relaxation Studies of Micellar Solutions of Ionic Surfactants, J. Phys. Chem., 80:905.CrossRefGoogle Scholar
- Birks, J. B., 1970, Photophysics of Aromatic Molecules, Chapter 7, in: “Excimers”, Wiley-Interscience, New York.Google Scholar
- Gianturco, S. H., and Bradley, W. A., 1987, Lipoprotein Receptors, in: “Plasma Lipoproteins”, A. M. Gotto, Jr., ed., Elsevier Publishing Company, New York.Google Scholar
- Jonas, A., 1987, Lecithin Cholesterol Acyltransferase, in: “Plasma Lipoproteins”, A. M. Gotto, Jr., ed., Elsevier Publishing Company, New York.Google Scholar
- Lange, Y., 1986, Molecular Dynamics of Bilayer Lipids, in: “The Physical Chemistry of Lipids”, D. M. Small, ed., Plenum Press, New York.Google Scholar
- Mantulin, W. W., and Pownall, H. J., 1983, Plasma Lipoproteins: Fluorescence as a Probe of Structure and Dynamics, in: “Excited States of Biopolymers”, R. F. Steiner, ed., Plenum Press, New York.Google Scholar
- Nakagawa, T., 1974, Critical Examination of Published Data Concerning the Rate of Micelle Dissociation and Proposal of a New Interpretation, Colloid and Polymer Sci., 252:55.Google Scholar
- Pownall, H. J., Homan, R., and Massey, J. B., 1987, Pyrene-labeled Amphiphiles: Dynamic and Structural Probes of Membranes and Lipoproteins, SPIE, 743:137.Google Scholar
- Tall, A., Swenson, T., Hesler, C., and Granot, E., 1987, Mechanisms of Facilitated Lipid Transfer Mediated by Plasma Lipid Transfer Proteins, in: “Plasma Lipoproteins”, A. M. Gotto, Jr., ed., Elsevier Publishing Company, New York.Google Scholar
- Tanford, C., 1980, in: “The Hydrophobic Effect”, 2nd Edition, Wiley Interscience, New York.Google Scholar