Figure 6.

Simultaneously mutating the three conserved Cys residues to Ser reduces interaction with the exosome. (A) TAP-tagged Rrp44 containing either a wild-type or mutated CR3 motif were purified from yeast. The lysate (left) and bound (right) fractions were analyzed by western blot with antibodies for the TAP tag (top), the exosome subunit Rrp4p (middle) or the control protein Pgk1p (bottom). (B) The rrp44–yrd allele that contains Y40A, R42A and D44A mutations has a slow growth phenotype that resembles that of rrp44–CR3. The experiment was performed using the plasmid shuffle as described in Figure 2.