1. Department of Biological Chemistry, University of California Los Angeles School of Medicine, Los Angeles, California 90024;
2. Ahmanson Center for Advanced EM & Imaging, House Ear Institute, Los Angeles, California 90057;
3. Institute for Pure and Applied Mathematics, University of California at Los Angeles, Los Angeles, California 90095; and
4. Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037