1. Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555-1068, United States
2. Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
3. Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
4. Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
5. Program in Molecular Medicine, Hospital for Sick Children Research Institute, Toronto, Ontario M5G 0A4, Canada