1. European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
2. SIB Swiss Institute of Bioinformatics, Centre Medical Universitaire, 1 rue Michel Servet, 1211 Geneva 4, Switzerland
3. Protein Information Resource, Georgetown University Medical Center, 3300 Whitehaven Street NW, Suite 1200, WA 20007, USA
4. Protein Information Resource, University of Delaware, 15 Innovation Way, Suite 205, Newark DE 19711, USA