1. Division
of Immunology, Beckman Research Institute of the City of Hope, 1500 East Duarte Rd, Duarte, California 91010, United States
2. Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland 20852, United States
3. MRC
Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis
Crick Avenue, Cambridge CB2 0QH, United Kingdom