Figure 5.

Mutation of the putative catalytic residue in the QIP exonuclease domain abolished QIP’s function in siRNA processing. (A,B) Northern blot analyses of al-1 siRNA by native (A) and denaturing (B) gels showing that the expression of Myc-QIP complements the siRNA processing defects in the qip^ko strain. (C) Western blot analysis using an anti-QIP antibody showing the overexpression of Myc-QIP and Myc-QIP(H504A) in the qip^ko strains. Amido black-stained membrane is shown below. (D) Northern blot analyses of al-1 siRNA in a native gel showing that the expression of Myc-QIP(H504A) cannot complement the siRNA-processing defects in the qip^ko strain. In A and B, three independent qip^ko,Myc-QIP,dsal-1 strains and in D, two independent qip^ko,Myc-QIP(H504A),dsal-1 strains were used.