Enables DNA-binding transcription repressor activity, RNA polymerase II-specific and RNA polymerase II cis-regulatory region sequence-specific DNA binding activity. Acts upstream of or within negative regulation of transcription by RNA polymerase II. Predicted to be located in nucleoplasm. Predicted to be active in nucleus. Is expressed in facial ganglion; glossopharyngeal ganglion; trigeminal ganglion; and vagus ganglion. Orthologous to human CC2D1B (coiled-coil and C2 domain containing 1B). [provided by Alliance of Genome Resources, Apr 2022]