1. Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA-94143.
2. Department of Physics, University of California, San Diego, La Jolla, CA 92093.
3. Hormone Research Institute, University of California, San Francisco, San Francisco, CA 94143.
4. Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA-94143.