Metalloprotease that acts as a negative regulator of the Wnt signaling pathway by mediating the cleavage of the N-terminal residues of a subset of Wnt proteins. Following cleavage, Wnt proteins become oxidized and form large disulfide-bond oligomers, leading to their inactivation. Able to cleave wnt8. Required for head formation. Divalent metal cations. Mn(2+) or Co(2+). Was named TIKI in reference to large-headed humanoid in Polynesian mythology. Belongs to the TIKI family.