Figure 3. Proteasome was defective in not4Δ cells but not in ccr4Δ cells.

A. Total cellular extracts were prepared from wild-type, caf1Δ, ccr4Δ, and not4Δ cells and loaded on 3.5% native gels. After electrophoresis gels were incubated with Suc-LLVY-AMC to analyze the proteasome activity in the absence (-SDS) and then in the presence (+SDS) of 0.02% SDS to detect the latent CP activity. The positions of double (RP₂-CP) and single (RP₁-CP) capped proteasomes and CP alone are indicated on the left. B. RPs were purified from wild-type, caf1Δ, ccr4Δ, and not4Δ cells, loaded on a gradient 3–12% native gel and then analyzed for activity (upper panel). The same purified material was analyzed by SDS-PAGE and western blot with antibodies against the RP subunit (Rpt1) and with antibodies against CP subunits (α1-7) (lower panel).