Fig. 4.

Hydrolysis of differently branched polyubiquitin chains by SARS-CoV PLpro and USP5. Lys48-linked Ub2-7 (lanes 2–4) and Lys63-linked Ub2-7 (lanes 5–7) were incubated for 2 h at 37 °C with PLpro (lanes 3 and 6) or USP5 (lanes 4 and 7). Enzymes and substrates were present at 8 μg/mL and 200 μg/mL, respectively. Proteins were resolved by a 10% SDS–PAGE and revealed by Coomassie blue staining. The molecular weights of the marker proteins are indicated on the left of the gel (in kDa). Arrowheads indicate the positions of PLpro and USP5.