1. Contribution from Department of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel, Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel, Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China, and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Foundation for Medical Education and Research, 200 First...