1. Wolfson Institute for Biomedical Research, University College London, Cruciform Building, Gower Street, London WC1E 6AE, United Kingdom, Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, and Department of Pharmacology, University of California, Los Angeles School of Medicine, Center for the Health Sciences, Los Angeles, California 90095