European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK, Swiss-Prot group, Swiss Institute of Bioinformatics, Centre Medical Universitaire, 1211 Geneve, Switzerland, Database Center for Life Science (DCLS), Research Organization of Information and Systems, 178-4-4 Wakashiba, Kashiwa, Chiba 277-0871, Japan, Stanford Center for Biomedical Informatics Research, Stanford University, CA 94305-5479, USA and Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK.