1. Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.
2. Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA.
3. Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, USA.
4. Department of Molecular Physiology and Biological Physics and Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22903, USA.
5. Institute for Protein Design, University of Washington, Seattle, WA 98195, USA.
6. Department of Molecular Engineering and Sciences, University of Washington, Seattle, WA 98195, USA.
7. Department of Chemistry and Biochemistry, Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, OH 43210, USA.
8. TC Jenkins Department of Biophysics Johns Hopkins University, Baltimore, MD 21218, USA.