DNA and RNA polymerase Protein Data Bank (PDB) IDs connected by Medical Subject Headings (MeSH) terms. (a) The PubNet graph resulting from the queries 'DNA polymerase 2004[dp]' and 'RNA polymerase 2004[dp]'. (b) A magnified view showing several PDB IDs that were present in papers returned by the first query. PDB IDs that were only returned by the 'DNA' query are blue, and those returned by both queries are shown in green. The green nodes correspond to structures of DNA primase. (c) A magnified view of several RNA polymerase PDB IDs.