1. Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States
2. Scripps Research Biophysics and Biochemistry Core, The Scripps Research Institute, La Jolla, California 92037, United States
3. Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States