The database iPfam, available at http://ipfam.org, catalogues Pfam domain 
interactions based on known 3D structures that are found in the Protein Data 
Bank, providing interaction data at the molecular level. Previously, the iPfam 
domain-domain interaction data was integrated within the Pfam database and 
website, but it has now been migrated to a separate database. This allows for 
independent development, improving data access and giving clearer separation 
between the protein family and interactions datasets. In addition to 
domain-domain interactions, iPfam has been expanded to include interaction data 
for domain bound small molecule ligands. Functional annotations are provided 
from source databases, supplemented by the incorporation of Wikipedia articles 
where available. iPfam (version 1.0) contains >9500 domain-domain and 15 500 
domain-ligand interactions. The new website provides access to this data in a 
variety of ways, including interactive visualizations of the interaction data.