1. Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milano,
Italy
2. Membrane Biophysics, Technical University of Darmstadt, Schnittspahnstrasse
3, 64287 Darmstadt, Germany
3. Department of Structural Biology, University of Kiel, Leibnizstrasse 11, 24098 Kiel,
Germany
4. CNR-IBF, Via Celoria 26, 20133 Milan, Italy