1. Centre for Biochemistry and Molecular Cell Biology, University of Göttingen, 37073 Göttingen, Germany.
2. Max-Planck-Institute for Experimental Medicine, 37075 Göttingen, Germany.
3. Max-Planck-Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
4. Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany.
5. BioTec, TU Dresden, 01307 Dresden, Germany.