Glycosphingolipids in mammalian cells appear to be localized almost exclusively in the external surface of the plasma membrane. These lipids have been known for some years to act as antigenic determinants and mediators of immune responses. Recent work suggests that specific glycosphingolipids may serve as receptors for toxins, viruses and some peptide hormones. There is also a growing body of evidence associating alterations in cell glycosphingolipids with normal process such as growth, differentiation, development and aging and also with oncogenic transformation in many cell types. In addition glycosphingolipids seem to be involved in cell-cell interactions and recognition. Although there is considerable information about the molecular structure of many glycosphingolipids, relatively little is known about the organizations of molecules of this class in phospholipid bilayers and the bilayers of biological membranes. It seems certain that their molecular organization is a critical parameter underlying many of the functions of glycosphingolipids. The research supported by this grant centers on the investigation of the biologically relevant system properties of lipid bilayers from well characterized phospholipids and cholesterol which contain variable amounts of glycosphingolipids of the types found in mammalian cell plasma membranes. Emphasis will be placed on the examination of bilayers in the form of single lamellar vesicles which have glycosphingolipid incorporated only on the outer surface; a system which is the analog of the plasma membrane bilayer. Multilamellar liposomes as well as large and small unilamellar vesicles will be utilized in this work which will depend upon a variety of physical techniques including fluorescent probes and NMr spectroscopy (1H, 2H, 13C and 31P), scanning calorimetry, partial molal volume measurement, autocorrelation light scattering as well as hydrodynamic methods to characterize vesicle dispersions. These studies complement a freeze-etch electron microscopic investigation carried out on similar systems as well as on selected biological membranes as a collaborative effort with Dr. Thomas Tillack in the Department of Pathology.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37GM023573-14
Application #
3484475
Study Section
Biophysical Chemistry Study Section (BBCB)
Project Start
1977-09-09
Project End
1993-12-31
Budget Start
1991-01-01
Budget End
1991-12-31
Support Year
14
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of Virginia
Department
Type
Schools of Medicine
DUNS #
001910777
City
Charlottesville
State
VA
Country
United States
Zip Code
22904
Pool, C T; Thompson, T E (1999) Methods for dual, site-specific derivatization of bovine pancreatic trypsin inhibitor: trypsin protection of lysine-15 and attachment of fatty acids or hydrophobic peptides at the N-terminus. Bioconjug Chem 10:221-30
Sugar, I P; Thompson, T E; Biltonen, R L (1999) Monte Carlo simulation of two-component bilayers: DMPC/DSPC mixtures. Biophys J 76:2099-110
Pool, C T; Thompson, T E (1998) Chain length and temperature dependence of the reversible association of model acylated proteins with lipid bilayers. Biochemistry 37:10246-55
Piknova, B; Marsh, D; Thompson, T E (1997) Fluorescence quenching and electron spin resonance study of percolation in a two-phase lipid bilayer containing bacteriorhodopsin. Biophys J 72:2660-8
Bar, L K; Barenholz, Y; Thompson, T E (1997) Effect of sphingomyelin composition on the phase structure of phosphatidylcholine-sphingomyelin bilayers. Biochemistry 36:2507-16
Schram, V; Thompson, T E (1997) Influence of the intrinsic membrane protein bacteriorhodopsin on gel-phase domain topology in two-component phase-separated bilayers. Biophys J 72:2217-25
Palestini, P; Allietta, M; Sonnino, S et al. (1995) Gel phase preference of ganglioside GM1 at low concentration in two-component, two-phase phosphatidylcholine bilayers depends upon the ceramide moiety. Biochim Biophys Acta 1235:221-30
Sankaram, M B; Marsh, D; Gierasch, L M et al. (1994) Reorganization of lipid domain structure in membranes by a transmembrane peptide: an ESR spin label study on the effect of the Escherichia coli outer membrane protein A signal peptide on the fluid lipid domain connectivity in binary mixtures of dimyristoy Biophys J 66:1959-68
Almeida, P F; Vaz, W L; Thompson, T E (1993) Percolation and diffusion in three-component lipid bilayers: effect of cholesterol on an equimolar mixture of two phosphatidylcholines. Biophys J 64:399-412
Almeida, P F; Vaz, W L; Thompson, T E (1992) Lateral diffusion and percolation in two-phase, two-component lipid bilayers. Topology of the solid-phase domains in-plane and across the lipid bilayer. Biochemistry 31:7198-210

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