1. Whitehead Institute for Biomedical Research (WIBR), Cambridge, MA 02142, USA.
2. Department of Chemistry, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA.
3. Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
4. Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA.
5. Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA.
6. Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38018, USA.
7. Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
8. Howard Hughes Medical Institute (HHMI), Department of Biology, MIT, Cambridge, MA 02139, USA.