Source:http://linkedlifedata.com/resource/umls/id/C1709740
NCI: Pfam is a large collection of multiple sequence alignments and hidden Markov models covering many common protein domains and families. For each family in Pfam you can 1) look at multiple alignments; 2) view protein domain architectures; 3) examine species distribution; 4) follow links to other databases; and 5) view known protein structures. (http://www.sanger.ac.uk/Software/Pfam/)