Figure 3.

Isopeptidase activity of USP7 mutants for polyubiquitinated PCNA. A, schematic representation of the structure of USP7 and its mutants. An alignment of PIPL1 and PIPL2 with the PIP-consensus sequence is shown. B, the reactions were performed with the indicated mutants and analyzed as described in Fig. 1A. C–L, quantified data of isopeptidase activity for polyubiquitinated PCNA. The relative amounts of reaction products were calculated as described in Fig. 1B. The amounts of unmodified PCNA generated in the reactions with the indicated concentrations of ^hisPL1 (C), ^hisΔN (D), ^hisΔN/PL2 (E), ^hisΔN/UL2 (F), or ^his7CD (G) and the amounts of remaining ubiquitinated PCNA in the reactions with the indicated concentrations of ^hisPL1 (H), ^hisΔN (I), ^hisΔN/PL2 (J), ^hisΔN/UL2 (K), or ^his7CD (L) are shown. The averages of at least two independent experiments were plotted. In most cases, the error bars were smaller than the symbols.