This purified polyclonal antibody reacts with ubiquitin by ELISA and western blot. Although not tested, this antibody is likely functional in immunohistochemistry and immunoprecipitation. For detection of free Ub by western blotting use Tris-Tricine SDS-PAGE and autoclaved nitrocellulose filters after the transfer and before blocking and addition of anti-Ub antibodies. Details on western blotting procedures are found in Mimnaugh et al., (1999 and 2002).