The CATH domain structure database: new protocols and classification levels give a more comprehensive resource for exploring evolution. - Lesley H. Greene; Tony E. Lewis; Sarah Addou; Alison L. Cuff; Timothy Dallman; Mark Dibley; Oliver Redfern; Frances M. G. Pearl; Rekha Nambudiry; Adam James Reid; Ian Sillitoe; Corin Yeats; et al. (Nucleic Acids Res., 2007)