UniProt: the Universal Protein Resource Lai-Su Yeh1, UniProt Consortium2 1 Protein Information Resource, Georgetown University Medical Center, Washington, DC 20057 2 European Bioinformatics Institute (EBI), Hinxton, UK; Protein Information Resource (PIR), Washington, DC, USA; Swiss Institute of Bioinformatics (SIB), Geneva, Switzerland Abstract UniProt is the most comprehensive catalog of protein sequence and function, produced by EBI, PIR and SIB. It has three components optimized for different uses. The UniProt Knowledgebase is an expertly curated database. The UniProt Archive provides a comprehensive sequence repository. UniProt Reference Clusters merge sequences based on sequence identity to speed searches. The UniProt Team