Enables RNA polymerase II-specific DNA-binding transcription factor binding activity. Acts upstream of or within several processes, including gland morphogenesis; neurogenesis; and regulation of transcription by RNA polymerase II. Located in cytoplasm and nucleus. Is expressed in several structures, including alimentary system; central nervous system; immune system; sensory organ; and urinary system. Used to study osteoporosis. Orthologous to human ID4 (inhibitor of DNA binding 4, HLH protein). [provided by Alliance of Genome Resources, Apr 2022]