1. Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
2. Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
3. Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
4. Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037
5. University of Maryland School of Medicine, Baltimore, Maryland 21201