Gerald Feigenson
Professor of Biochemistry & Physical Biochemistry

Phone

607-255-4744

Address

Department of Molecular Biology & Genetics
201 Biotechnology Building
Cornell University
Ithaca, NY 14853-2703

Email

Web Sites

Background

Jerry Feigenson is a Professor of Biochemistry, Molecular and Cell Biology. He received a B.S. in Chemistry from the Rensselaer Polytechnic Institute in 1968, and a Ph.D. in Chemistry from the California Institute of Technology in 1974. He joined the Cornell faculty in 1974, after a brief postdoctoral study at Oxford University. He has been a Visiting Professor of Physics at Keio University in Japan, a Visiting Scholar at Scripps Institution of Oceanography, an Established Investigator of the American Heart Association.

Research Description

We are interested in the physical and chemical properties of biomembranes. This bilayer state of matter poses both experimental and conceptual challenges. Our goal is to understand the interactions that control the tendency of each component of the membrane bilayer to cluster, to change phase, to transfer to another membrane, or to chemically react. Thus, the thermodynamics of mixing plays a key role for interpreting our experiments and calculations.

The biomembrane can be considered as a nonrandom mixture of lipids and proteins. Some components, such as phosphatidylserine or cholesterol, can induce separated fluid bilayer phases within the biomembrane. The cholesterol-rich phase is particularly fascinating, because it is as highly ordered as a crystal, yet is actually a fluid bilayer.

Our laboratory uses a variety of chemical and physical techniques to study real and model biomembranes. We synthesize various kinds of phospholipids, including spin-labeled, fluorophor-labeled, and perdeuterated phospholipids. We use nuclear magnetic resonance and electron spin resonance spectroscopies to examine the state of motion and order in the bilayer. Light-scattering, optical microscopy, and X-ray diffraction enable detection and identification of different lipid phases. We use various fluorescence spectroscopic methods, especially fluorescence quenching, to study bilayer behavior and partition of lipids or proteins between coexisting membrane phases.

Recently, we have been able to describe the phase diagram of a 3-component bilayer mixture that is a reasonable model for mammalian plasma membranes, DPPC/DLPC/cholesterol. Understanding this phase behavior required experiments using confocal fluorescence microscopy, fluorescence resonance energy transfer, and pyrene excimer/monomer ratios. A surprising result is that some regions of the diagram show nano-scale "phase" separation that might be related to the so-called lipid rafts postulated to exist in plasma membranes.

Publications

Chiang, Y-W., Zhao, J., Wu, J., Shimoyama, Y., Freed, J. H. and Feigenson, G. W.   2005.  New method of determining tie-lines in coexisting membrane phases using spin-label ESR. Biochim. Biophys. Acta, 1668, 99-105.

Korlach, J., Baumgart, T., Webb, W.W. and Feigenson, G.W.  2005.  Detection of motional heterogeneities in lipid bilayer membranes by dual probe fluorescence correlation spectroscopy.  Biochim. Biophys. Acta, 1668, 158-163.

Shogomori, H., Hammond, A. T., Ostermeyer-Fay, A. G., Barr, D. J., Feigenson,G. W., London, E. and Brown, D. A.   2005. Palmitoylation and intracellular-domain interactions both contribute to raft targeting of linker for activation of T cells (LAT), J. Biol. Chem. 280: 18,931-18,942.

Hammond, A.T., Heberle, F.A., Baumgart, T., Holowka, D., Baird, B. and Feigenson, G.W.  2005. Crosslinking a Lipid Raft Component Triggers Liquid Ordered–Liquid Disordered Phase Separation in Model Plasma Membranes.  Proc. Nat. Acad. Sci. USA 102: 6320-6325.

Buboltz, J.T. and Feigenson, G.W.  2005.  Phospholipid Solubility Determined by Equilibrium Distribution between Surface and Bulk Phases.  Langmuir, 21: 6296-6301.

Click here for Dr. Feigenson's PubMed listing.