Covalent modification of proteins with ubiquitin plays an important role in a wide array of
cellular processes (Hershko and Ciechanover, 1998; Pickart, 2004). For this reason an
increasing number of investigators in diverse research fields are confronted with the
question whether their favorite proteins are ubiquitinated. Experiments to demonstrate
covalent modification with ubiquitin in vivo can be quite challenging because of low steady‐
state levels of the ubiquitinated forms caused by degradation by the 26S proteasome and/or …