Enables PDZ domain binding activity and zinc ion binding activity. Involved in neuroblast fate specification; regulation of canonical Wnt signaling pathway; and segment polarity determination. Located in cytosol and nucleus. Is expressed in several structures, including cuboidal/columnar epithelium; dorsal epidermis primordium; dorsal-ventral compartment boundary of the wing disc; head epidermis primordium; and imaginal disc. Orthologous to human NKD1 (NKD inhibitor of WNT signaling pathway 1) and NKD2 (NKD inhibitor of WNT signaling pathway 2).