FIGURE 4.

Increasing ataxin-3 DUB activity by mutagenesis. A, cleavage of Lys-48-linked ubiquitin dimers by the Josephin domains of wild-type and mutant ataxin-3 (Atx3) and ATXN3L is shown. Ubiquitin dimers were incubated with the Josephin domain for the times indicated. B, cleavage of Lys-63-linked ubiquitin dimers is shown. C–E, time course of cleavage of the ubiquitin-His₆ construct by various Josephin domains is shown. Molecular weight markers (MW) are the same in panels C, D, and E. C, wild-type ataxin-3 is shown. D, ATXN3L is shown. E, the ataxin-3 triple mutant S12F/R59L/T60A is shown.