... interactions between Nop53p and the exosome subunits using the two-hybrid system, but no positive interaction was detected[31]. Therefore, we tested the interaction between Nop53p and some of the exosome ... concentrated in the nucleolus. These resultsraised the question of whether any of the truncatedmutants of Nop53p, when under control of a constitu-tive promoter, could complement the growth of the con-ditional ... 7Spre-rRNA, thereby regulating the function of the complex. In the absence of Nop53p, the exosome isnot efficiently directed to the 7S pre-rRNA for pro-cessing, leading to the accumulation of its...