1. Department of Physiology, McGill University, Montréal, Quebec H3G 1Y6, Canada.
2. Departments of Medicine and Physiology, University of California, San Francisco, San Francisco, CA 94143–0521, USA.
3. MTA-SE Molecular Biophysics Research Group, Hungarian Academy of Sciences, 1444 Budapest, Hungary.
4. Department of Biophysics and Radiation Biology, Semmelweis University, 1444 Budapest P.O. Box 263, Hungary.
5. Department of Pathology, University of California, San Francisco, San Francisco, CA 94143–0511, USA.
6. Department of Biochemistry, McGill University, Montréal, Quebec H3G 1Y6, Canada.
7. Groupe de Recherche Axé sur la Structure des Protéines (GRASP), McGill University, Montréal, Quebec H3G 1Y6, Canada.