WAP Four Disulfide Core Domain Protein 9 (WFDC9)

The WAP-type four-disulfide core (WFDC) domain, or WAP signature motif, contains eight cysteines forming four disulfide bonds at the core of the protein, and functions as a protease inhibitor in many members of the WFDC domain family. WFDC9 encodes a protein which contains a WFDC domain, and is thus a member of the WFDC domain family. This gene and several other gene family members are clustered at 20q13.12. Although this protein was isolated in a region containing several WAP proteins and was defined as a WAP protein, it does not contain a classical WAP domain. Characteristic features of the genes are that the upstream promoter regions are devoid of TATA-boxes and that the coding nucleotides are divided into distinct exons for the signal peptide and for each WAP domain.