The InterPro database, an integrated documentation resource for protein families, domains and functional sites.
Apweiler R, Attwood TK, Bairoch A, Bateman A, Birney E, Biswas M, Bucher P, Cerutti L, Corpet F, Croning MD, et al. Nucleic Acids Res. 2001 Jan 1; 29(1):37-40.