1. Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA.
2. Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA.
3. Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224, USA.
4. Howard Hughes Medical Institute, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA.