1. Department of Neurology, University of California, San Francisco, San Francisco, California 94143, United States
2. The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California 94143, United States
3. Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
4. Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
5. Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
6. Neuroscience Program, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States