1. Institute of Physical Chemistry, Heidelberg University, D-69120 Heidelberg, Germany
2. Institute of Cardiovascular Sciences, College of Medical and Dental Sciences & School of Chemistry, University of Birmingham, Birmingham, B152TT UK
3. Centre of Membrane Proteins and Receptors (COMPARE), The Universities of Birmingham and Nottingham, The Midlands, Birmingham, B15 2TT UK
4. Faculty of Biosciences, Heidelberg University, D-69120 Heidelberg, Germany