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Our main research interests are in determining, at the molecular level, how cell membranes are organized and how that organization relates to function. The primary molecular building blocks of cell membranes are lipids, amphipathic molecules that assemble into two opposed leaflets forming a bilayer, and proteins. Elucidating organization is a challenging problem as the components are frequently in motion while interacting weakly for short periods. The research breaks down into two general areas:
Investigate the organization of cell membranes to understand how form translates into function. Currently there is much interest in the role that lipids, once thought passive players, have in cellular function. This is due to a number of facts about lipids that have come to light in recent years: 1) There is considerable heterogeneity in lipid chemistry. 2) Lipid composition varies greatly between cell type, organelle, and leaflet. 3) There is evidence, and much interest, in the idea that lipid composition within a leaflet is not uniform as a result of the heterogeneity. 4) Some lipids provide discrete protein binding domains and thus can play a crucial role in targeting. 5) Lipid chemistry can be remodeled in the membrane by the action of proteins involved in signaling pathways. By investigating lipid-lipid interactions as well as lipid-protein and protein-protein we hope to understand how these interactions translate to diverse functions such as vesicle budding, immunological responses, and transport of ions.
Develop unique and novel methodologies for these studies. One of the great challenges in this research is the lack of an ideal analytical tool for studying the system; an ideal tool would allow one to track individual lipids in real time and identify their chemical composition. As a result, we focus part of our efforts on developing a synergy between several surface analytical techniques in order to obtain as complete a picture as possible. The techniques include atomic force microscopy, epi-fluorescence microscopy, and various surface spectroscopic techniques.
University of Illinois at Urbana-Champaign.
33. F. Haque, L.R. Cambrea, J.-C. Rochet and J.S. Hovis, “Adsorption of a-Synuclein on Lipid Bilayers Containing Phosphatidic Acid: Formation of Two Different Protein Environments” submitted 32. K.J. Seu, E.R. Lamberson and J.S. Hovis, “Using Ionic Strength to Control Liquid-Ordered/Liquid-Disordered Separation” J. Phys. Chem. B, 111, 6289-6292 (2007).
31. L.R. Cambrea, F. Haque, J.L. Schieler, J.-C. Rochet and J.S. Hovis, “Effect of Ions on the Organization of DOPC/DOPA Bilayers” 93, 1630-1638 (2007).
30. L.R. Cambrea and J.S. Hovis, “Formation of Three-Dimensional Structures in Supported Lipid Bilayers” Biophys. J . 92, 3587-3594 (2007).
29. K.J. Seu, A.P. Pandey, F. Haque, E.A. Proctor, A.E. Ribbe, and J.S. Hovis, “Effect of Surface Treatment on Diffusion and Domain Formation in Supported Lipid Bilayers” Biophys. J., 92, 2445-2450 (2007).
28. K.J. Seu, L.R. Cambrea, R.M. Everly and J.S. Hovis, “Influence of Lipid Chemistry on Membrane Fluidity: Tail Density and Hydrogen Bonding” Biophys. J., 91, 3727-3735 (2006)
27. C.C. Logisz and J.S. Hovis, “Effect of Salt Concentration on Membrane Lysis Pressure” Biochem. et. Biophys. Acta, 1717, 104-108 (2005).
26. M.C. Hull, L.R. Cambrea and J.S. Hovis, “Infrared Spectroscopy of Fluid Lipid Bilayers” Anal. Chem., 77, 6096-6099 (2005).
25. M.C. Hull, D.S. Sauer and J.S. Hovis, “The Influence of Lipid Chemistry on the Osmotic Response of Cell Membrane : Effect of Non-Bilayer Forming Lipids” J. Phys. Chem. B, 108, 15890-15895 (2004).
From postdoctoral work
24. J.S. Hovis, and S.G. Boxer, “Patterning and Composition Arrays of Supported Lipid Bilayers by Microcontact Printing,” Langmuir, 17, 3400-3405 (2001).Þ Profiled in Analytical Chemistry: August 1, 2001; p.406A
23. L.A. Kung, L.C. Kam, J.S. Hovis, and S.G. Boxer, “Patterning Hybrid Surfaces of Proteins and Supported Lipid Bilayers,” Langmuir, 16, 6773-6776 (2000).
From graduate work
21. J.N. Russell Jr., J.E. Butler, G.T. Wang, S.F. Bent, J.S. Hovis, R.J. Hamers and M.P. D’Evelyn, “p Bond Versus Radical Character of the Diamond(100)-2x1 Surface,” Mat. Chem. Phys., 72, 147-151 (2001).
20. J.S. Hovis, S.K. Coulter, R.J. Hamers, M.P. D’Evelyn, J.N. Russell Jr., and J.E. Butler, “Surface Cycloaddition Chemistry of Cyclopentene on the Diamond(001)-2x1 Surface,” J. Am. Chem Soc., 122, 732-733 (2000).
19. M.P. Schwartz, M.D. Ellison, S.K. Coulter, J.S. Hovis, and R.J. Hamers, “Selectivity in Cycloaddition Chemistryof p-Conjugated Organic Molecules on the Si(001) Surface,” J. Am. Chem. Soc., 122, 8529-8538 (2000).
18. S.W. Lee, J.S. Hovis, S.K. Coulter, R.J. Hamers, and C.M. Greenlief, “Cycloaddition Chemistry on Germanium(001) Surfaces: The Adsorption and Reaction of Cyclopentene and Cyclohexene,” Surface Science, 462, 6-18 (2000).
17. R.J. Hamers, S.K. Coulter, M.D. Ellison, J.S. Hovis, D.F. Padowitz, M.P. Schwartz , C.M. Greenlief , J.N. Russell, Jr., “Cycloaddition Chemistry of Organic Molecules with Semiconductor Surfaces,” Accounts of Chemical Research, 33, 617-624 (2000).
15. S.K. Coulter, J.S. Hovis, M.D. Ellison, and R.J. Hamers, “Reactions of Substituted Aromatic Hydrocarbons with the Si(001) Crystal Surface,” J. Vac. Sci. Tech. A, 18, 1965-1970 (2000).
14. J.S. Hovis, R.J. Hamers, C.M. Greenlief, “Preparation of Clean and Smooth Ge(001)-2x1 Surfaces by Resistive Heating for Scanning Tunneling Microscopy Studies,” Surface Science, 440, L815-L819 (1999).
13. R.J. Hamers, J.S. Hovis, C.M. Greenlief, and D.F. Padowitz, “Scanning Tunneling Microscopy of Organic Molecules and Monolayers on Silicon and Germanium (001) Surfaces,” Jpn. J. Appl. Phys., 38, 3879-3887 (1999). 12. M.D. Ellison, J.S. Hovis, H. Liu, R.J. Hamers, “Cycloaddition Chemistry on Silicon(001) Surfaces: The Adsorption of Azo-tert-butane,” J. Phys. Chem. B, 102, 8510-8518 (1998).
11. J.S. Hovis, H. Liu, and R.J. Hamers, “Cycloaddition Chemistry of 1,3-Dienes on the Silicon(001) Surface: The Competition Between [4+2] and [2+2] Reactions,” J. Phys. Chem. B, 102, 6873-6879 (1998).
10. J.S. Hovis, H. Liu and R.J. Hamers, “Cycloaddition Chemistry and Formation of Ordered Organic Monolayers on Silicon (001) Surfaces,” Surface Science, 404, 1-7 (1998).
9. J.S. Hovis, H. Liu, and R.J. Hamers, “Scanning Tunneling Microscopy of Cyclic Unsaturated Organic Molecules on the Silicon(001) Surface,” Applied Physics A, 66, S553-S557 (1998).
8. R.J. Hamers, J.S. Hovis, and H. Liu, “Scanning Tunneling Microscopy of Ordered Organic Monolayer Films on Si(001),” Acta Physica Polonica A, 93, 289-295 (1998).
7. J. S. Hovis and R.J. Hamers, “Structure and Bonding of 1,3,5,7-Cyclooctatetraene on Si(001) Surfaces: Surface Cycloaddition Chemistry of an Anti-aromatic Molecule,” J. Phys. Chem. B, 102, 687-692 (1998).
6. J.S. Hovis and R.J. Hamers, “Structure and Bonding of 1,5-Cyclooctadiene on Si(001) Surfaces,” J. Phys. Chem. B, 101,9581-9585 (1997).Þ Profiled in Science: J.T. Yates, 279, 335-336 (1998).
5. J.S. Hovis, S. Lee, H. Liu, and R.J. Hamers, “Controlled Formation of Organic Layers on Semiconductor Surfaces,” J. Vac. Sci. Tech. B, 15, 1153-1158 (1997).
4. R.J. Hamers, J. S. Hovis, S. Lee, H. Liu, and J. Shan, “Formation of Ordered, Anisotropic Organic Monolayers on the Si(001) Surface,” J. Phys. Chem. 101,1489-1492 (1997).
From undergraduate work
3. D.R. Stinebring, T.V. Smirnova, T.H. Hankins, J.S. Hovis, V.M. Kaspi, J.C. Kempner, E. Myers, and D.J. Nice, “Five Years of Pulsar Flux Density Monitoring: Refractive Scintillation and the Interstellar Medium,” The Astrophysical Journal, 593, 300-316 (2000).
2. C.H. Becker, C.R. Ayre, L. Moro, and J.S. Hovis, “Laser Postionization: Some Current Topics –Hard and Soft,” Secondary Ion Mass Spectroscopy 1994, 9, 15-19, (1994). 1. C.H. Becker and J.S. Hovis, “Surface Analysis by Photoionization at Very High Laser Intensities,” J. Vac. Sci. Tech. A, 12, 2352-2356 (1994).
Researchers should cite this work as follows:
Nano-Bio Workshop and nanoHUB Summer School,
NCSA, University of Illinois at Urbana-Champaign, July 30-31, 2007
(2008), "Controlling Membrane Organization: Effects of pH, Ions, and composition," https://nanohub.org/resources/4169.