FIG. 1.

Degradation of RFX5 by recombinant CPAFcp. CPAFcp was expressed as a fusion protein with GST as the fusion partner and the purified GST-CPAFcp was tested for its ability to degrade either the endogenous RFX5 in HeLa cell NE (A) or a recombinant human RFX5 (GST-RFX5) purified from a bacterial expression system (B). The degradation was carried out in a cell-free assay as described in Materials and Methods. CPAFcp was used at final concentrations of 0.05 (low), 0.2 (med), or 0.6 (high) μM, while the proteasome inhibitor lactacystin was used at 200 μM. A fusion protein containing GST and just the COOH-terminal portion of CPAFcp (GST-CPAFcp C terminus) failed to degrade either the endogenous or the recombinant RFX5 even at a final concentration of 2 μM. DMSO, dimethyl sulfoxide (a solvent used for dissolving lactacystin); ns, nonspecific binding.