BindingDB also integrates with the UniProtKB protein knowledgebase and the RCSB Protein Data Bank (PDB) . BindingDB assigns UniProtKB IDs to protein targets and uses UniProtKB's recommended protein names. UniProtKB in turn provides links from their protein records to corresponding targets in BindingDB, with their associated small molecule binding data. We also scan each protein-ligand pair in BindingDB against the protein-ligand structural data in the RCSB PDB looking for exact compound matches, and identify two sets of relevant structures. In one set (15,328 structures), the protein sequence identity is above 85%, and in the other ( , presence of so-called complex work units with molecular structures, and presence of tabular data associated with key words such as "IC50" and "Kd".