1. V. N. Malashkevich, Department of Structural Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
2. R. A. Kammerer, V. P. Efimov, T. Schulthess, J. Engel, Department of Biophysical Chemistry, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.