Enables RNA polymerase II-specific DNA-binding transcription factor binding activity and enzyme binding activity. Involved in several processes, including negative regulation of cold-induced thermogenesis; negative regulation of myofibroblast differentiation; and negative regulation of transcription involved in G1/S transition of mitotic cell cycle. Acts upstream of or within several processes, including hepatocyte apoptotic process; neuron development; and regulation of transcription by RNA polymerase II. Located in nucleus and spindle. Part of Rb-E2F complex. Is expressed in several structures, including alimentary system; central nervous system; hemolymphoid system; retina; and vibrissa. Human ortholog(s) of this gene implicated in nervous system cancer (multiple); osteosarcoma; prostate cancer; small cell carcinoma; and urinary bladder cancer. Orthologous to human RB1 (RB transcriptional corepressor 1). [provided by Alliance of Genome Resources, Apr 2022]