Professor Horst Vogel
Laboratory of Physical Chemistry
Ecole Polytechnique Federale de
Lausanne, Switzerland

Friday, August 19, 2011
2:00 pm (CT)
144 Loomis, CPLC

Abstract

Novel methodologies will be presented for investigating binding of ligands to cell surface receptors and subsequent activation of signaling reactions in single cells and in single, sub-micrometer sized vesicles with single molecule resolution. Our methods allow the isolation of attoliter-sized vesicles from living cells. Each of these cell-derived vesicles functions as an autonomous container capable to perform cellular signaling reactions. This miniaturization opens novel possibilities in functional proteomics such as multiplexing single cell analysis or investigating receptor mediated signaling. Several examples of cellular signaling reactions mediated by G protein coupled receptors such as olfactory receptors and ligand-gated ion channels (LGIC) will be reported. In the case of LGIC we probed the entire activation process of the human muscle acetylcholine receptor measuring simultaneously single molecule fluorescence ligand binding events and single channel gating. The distribution of time delays between these events indicate that upon ligand binding the receptor explores multiple, energetically similar conformational states towards channel opening. Our approach is of importance for elucidating ion translocation events across cell membranes.