Dkk-4

Dickkopf related protein 4 (Dkk4) is a member of the Dkk protein family that includes Dkk1, 2, 3, and 4. All four members are secreted proteins that are synthesized as precursor proteins with an Nterminal signal peptide and 2 conserved cysteinerich domains, which are separated by a linker region. Dkk proteins have potential furin type proteolytic cleavage sites, and short forms of Dkk2 and Dkk4 containing only the second cysteine-rich domain can be generated by proteolytic processing. Dkk proteins have distinct patterns of expression in adult and embryonic tissues, suggesting that they may play diverse roles in these tissues. The Dkk proteins have distinct effects on Wnt signaling. Dkk1 and Dkk4 are Wnt antagonists. Dkk3 has not been demonstrated to affect Wnt signaling, and Dkk2 acts as an agonist or antagonist, depending on the cellular context.