Enables frizzled binding activity. Acts upstream of or within positive regulation of JUN kinase activity. Located in cell-cell junction. Is expressed in several structures, including central nervous system; gut; hindlimb long bone; lung; and nose. Orthologous to human MAGI3 (membrane associated guanylate kinase, WW and PDZ domain containing 3). [provided by Alliance of Genome Resources, Apr 2022]