Biophysical Society Thematic Meeting

Liposomes, Exosomes, and Virosomes: From Modeling Complex

Membrane Processes to Medical Diagnostics and Drug Delivery

Tuesday Speaker Abstracts

Imagining Individual Receptors While Extracting Kinetic and Thermodynamic Parameters

Using FD-based AFM

David Alsteens

Université Catholique de Louvain, Louvain-La-Neuve, Belgium.

Currently, there is a growing need for methods that can quantify and map the molecular

interactions of biological samples, both with high-force sensitivity and high spatial resolution.

Force-distance (FD) curve-based atomic force microscopy is a valuable tool to simultaneously

contour the surface and map the biophysical properties of biological samples at the nanoscale.

This presentation reports the use of advanced FD-based technology combined with chemically

functionalized tips to probe the localization of specific sites on single native proteins and on

living cells at high-resolution. Using biochemically sensitive tips, we are able to locate specific

interaction sites on native protein at unprecedented resolution. We also introduce experimental

and theoretical developments that allow force-distance curve-based atomic force microscopy

(FD-based AFM) to simultaneously image native receptors in membranes and to quantify their

dynamic binding strength to native and synthetic ligands. These binding strengths provide kinetic

and thermodynamic parameters of individual ligand-receptor complexes.

Signal Transduction on Membrane Surfaces: The Roles of Space, Force, and Time

Jay T Groves

University of California, Berkeley, Berkeley, CA, USA.

Most intracellular signal transduction reactions take place on the membrane surface. The

membrane provides much more than just a surface environment on which signaling molecules

are concentrated. There is a growing realization that multiple physical and chemical mechanisms

allow the membrane to actively participate in the signaling reactions. Using a combination of

single molecule imaging and spectroscopic techniques, my research seeks to directly resolve the

actual mechanics of signaling reactions on membrane surfaces both in reconstituted systems and

in living cells. These observations are revealing new insights into cellular signaling processes as

well as some unexpected functional behaviors of proteins on the membrane surface.