RNA polymerase II degradation factor recruits the ubiquitination machinery to the RNA polymerase II for polyubiquitination, removal and degradation, when RAD26 fails to efficiently displace stalled RNA polymerase II. Also involved in telomere length regulation. Interacts with the RNA polymerase II in a DNA-damaged dependent manner. Interacts with RAD26. Binds DNA. Present with 3380 molecules/cell in log phase SD medium. Belongs to the DEF1 family.