Enables several functions, including DNA-binding transcription repressor activity, RNA polymerase II-specific; SMAD binding activity; and nucleic acid binding activity. Involved in negative regulation of transcription by RNA polymerase II. Acts upstream of or within negative regulation of transcription, DNA-templated. Located in nucleus. Is expressed in heart and hindlimb muscle. Orthologous to human PURB (purine rich element binding protein B). [provided by Alliance of Genome Resources, Apr 2022]