Towards defining the complement of mammalian WFDC-domain-containing proteins.

WFDC (whey/four-disulfide core)-domain-containing proteins are defined by the possession of one or more 40-50 amino acid domains that include eight conserved cysteine residues linked by four characteristic intramolecular disulfide bonds. Some also contain other structural domains, whereas in many the WFDC-domain is the only domain present. The WFDC-domain is not limited to mammals but is widespread across all lineages. There is increasing evidence to suggest that mammalian WFDC-domain-containing proteins are undergoing rapid molecular evolution and as might be expected they exhibit low levels of sequence similarity coupled with multiple examples of species-specific gene acquisition and gene loss. The characteristic structural domain (that is generally encoded by a single exon) makes these proteins relatively easy to identify in databases. This review will outline the repertoire of such domains within the mouse, but similar principles can be applied to the identification of all proteins within individual species.