Participates in the Wnt signaling pathway. Binds to DNA and acts as a repressor in the absence of ctnnb1, and as an activator in its presence. Required early in development for the establishment of the dorsal body axis in response to maternal Wnt signaling (By similarity). Interacts with csnk1e, ctnnb1, ctbp, dact1 and gsk3b. May interact with ase and tle4 (By similarity). Phosphorylated. Phosphorylation by csnk1e promotes binding to ctnnb1 while phosphorylation by gsk3b may reverse this effect (By similarity). Belongs to the TCF/LEF family.