UniProt strives to provide comprehensive literature citations on which UniProtKB protein annotations are based. Currently, there are ∼228 000 distinct PubMed citations associated with ∼4.2 million UniProtKB sequences and 67% of these citations are in UniProtKB/Swiss-Prot. Databases such as Entrez Gene and MODs (e.g. dictyBase, SGD, and MGI) also provide curated literature information, which reflect their priorities and focus. We have now integrated literature annotations from 11 external gene or protein databases, including GeneRIF of Entrez Gene (http://www.ncbi.nlm.nih.gov/projects/GeneRif), PDB (http://www.rcsb.org/pdb) and 9 MODs: SGD (http://www.yeastgenome.org), MGI (http://www.informatics.jax.org), GAD (geneticassociationdn.nih.gov), dictyBase (http://www.dictybase.org), ZFIN (http://www.zfin.org), WormBase (http://www.wormbase.org), TAIR (http://www.arabidopsis.org), RGD (rgd.mcw.edu) and FlyBase (http://www.flybase.org). These 11 external sources contribute ∼350 000 unique PubMed citations not yet annotated in UniProtKB, covering ∼188 000 UniProtKB entries. The additional bibliography is directly linked from the protein entry view on the UniProt website. We continue to identify more sources of bibliography information to enhance the UniProtKB bibliography and to allow scientific users to better explore the existing knowledge on their proteins of interest.
