Motifs in yeast WW domain proteins and WW sequence alignment. (a) Ten yeast proteins contain a total of thirteen WW domains. (b) Multiple sequence alignment of the 13 WW domains. The domains from Rsp5 and Prp40 are named corresponding to their occurrence from amino to carboxyl terminus. Conservation of the tryptophan residue at position 13 and the proline residue at position 39, as well as partial conservation of the tryptophan at position 36 define the WW domain (filled blue boxes). The sequences shown were purified as fusions to either MBP or GST. Residues boxed in red residues indicate the sequence determinants that put the WW domains into three different classes: groups I, II/III and IV . Six of the WW domains do not conform to any of the classifications.
Hesselberth et al. Genome Biology 2006 7:R30 doi:10.1186/gb-2006-7-4-r30