1. Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, United Kingdom, GlaxoSmithKline, Inc., 5 Moore Drive, Research Triangle Park, North Carolina 27709, and GlaxoSmithKline, Medicines Research Centre, Stevenage, Herts, SG1 2NY, United Kingdom