Figure 2.
Usp14 is catalytically active only in the presence of proteasomes. The top panel indicates the catalytically active DUBs detected in wild-type (wt) and axJ proteasome fractions in the presence and absence of recombinant Usp14. The preparations were incubated with HA-Ub-VS and probed with the anti-HA antibody 12C5. The locations of the two proteasome-bound DUBs are indicated to the right. The middle panel depicts total Usp14 detected by polyclonal Usp14 antisera. The blots also were probed with an antibody to the 19S proteasome component Rpt4 as a control.