Figure 6.

Isopeptidase activity of USP7 for diubiquitin with various linkages. A, each diubiquitin with the indicated linkage (240 fmol) was incubated with the indicated concentration of ^hisUSP7 for 10 min. The reaction products were analyzed by Western blotting with an anti-ubiquitin mAb. B, quantified data. Signal intensities of diubiquitin in (A) were measured, and the relative amount of diubiquitin was normalized to that at time 0. In the cases of Lys⁶- and Lys³³-linked diubiquitin, the substrates were reduced to ∼80% of the initial amount during a 10-min incubation without enzymes. The averages of two independent experiments were plotted. In most cases, the error bars were smaller than the symbols.