Component of the beta-catenin destruction complex required for regulating ctnnb1 levels through phosphorylation and ubiquitination, and modulating Wnt-signaling. Controls dorsoventral patterning via two opposing effects; down-regulates ctnnb1 to inhibit the Wnt signaling pathway and ventralize embryos, but also dorsalizes embryos by activating a Wnt-independent JNK signaling pathway. Homodimer (By similarity). Interacts with hwa; leading to promote the tankyrase-mediated degradation of axin1 (By similarity). Weakly and ubiquitously expressed throughout early development, and highly expressed in the anterior mesencephalon adjacent to the forebrain-midbrain boundary. ADP-ribosylated by tankyrase tnks and tnks2. Poly-ADP-ribosylated protein is recognized by rnf146, followed by ubiquitination at 'Lys-48' and subsequent activation of the Wnt signaling pathway. Ubiquitinated by rnf146 when poly-ADP-ribosylated, leading to its degradation and subsequent activation of the Wnt signaling pathway.