Dickkopf 3, like DKK1, DKK2, and DKK4, possesses an N terminal signal peptide and 2 conserved cysteine rich domains, which are separated by a linker region and contain 10 cysteine residues each. The second cysteine region has a putative lipid binding function that may facilitate WNT/DKK interactions at the plasma membrane. The linker region contains 50 to 55 amino acids in DKK1, DKK2, and DKK4, whereas in DKK3 it contains only 12 amino acids. All DKKs have several potential sites for cleava