Figure 2.

Isopeptidase activity of USP7 and USP2 for Lys⁶³-linked diubiquitin. A, Lys⁶³-linked diubiquitin substrate of 240 fmol was incubated with ^hisUSP7 (140 nm) or ^hisUSP2^CD (30 nm) for the indicated times. The reaction products were analyzed by Western blotting with an anti-ubiquitin mAb. B and C, quantified data. The reactions were performed with the indicated concentration of ^hisUSP7 (B) or ^hisUSP2^CD (C). Signal intensities of diubiquitin were measured, and the relative amount of diubiquitin was normalized to that at time 0. The averages of two independent experiments were plotted. In most cases, the error bars were smaller than the symbols. D, the data obtained at 10 min in the time course experiments described in (B) and (C) were replotted against enzyme concentrations.