Berlin 2005 – scientific programme

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AKB: Biologische Physik

AKB 200: Poster Session II

AKB 200.52: Poster

Tuesday, March 8, 2005, 17:00–19:00, Poster TU C

Monitoring individual odorant receptors in cultured mammalian cells — •Michael Prummer, Valerie Jacquier, Horst Pick, and Horst Vogel — Laboratory of Physical Chemistry of Polymers and Membranes, Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland

The olfactory system is a highly specialized chemo-sensor recognizing a myriad of compounds at very low concentrations. Human odorant receptors (ORs) constitute a multi-gene family of G-protein coupled receptors with about 450 members. Although many putative ORs have been cloned, the expression in heterologous systems has been complicated by the failure of these proteins to translocate efficiently to the plasma membrane. Here, single-molecule detection is an appropriate tool allowing for the investigation of single ORs in the membrane of living cells. Human OR17-40 was enzymatically labeled with Cy5 and expressed in HEK293 cells where ligand-induced Ca-signaling and internalization proved its structural integrity and the existence of a functional secondary messenger system. Single-molecule tracking wide-field microscopy was utilized to record trajectories of ORs, which were analyzed in terms of the microscopic diffusion coefficient of each molecule, and the probability distribution of the mean-square displacement, averaged over many molecules. Current investigations are focused on how the mobility of ORs is influenced by ligand activation. The ultimate goal is to monitor the fate of individual ORs from their resting state through ligand binding until desensitization occurs.