1. Institute of Physiology II, University of Münster, Germany (A.L.H., M.N.K., J.K.F., W.A.L.).
2. Department of Cellular and Molecular Medicine, The University of Arizona, Tucson (N.M.E.).
3. Biophysics Collaborative Access Team (BioCAT), Department of Biology, Illinois Institute of Technology, Chicago (D.L.N., W.M., T.C.I.).