FIGURE 2.

RPA and WRN directly interact with each other. For Far Western analysis (WB), purified RPA (A), WRN-E84A (B), and BSA (both, as a control for nonspecific binding) were immobilized on nitrocellulose membranes at the indicated concentrations. After blocking, membranes were then incubated in buffer containing 25 or 100 mm NaCl as indicated and either WRN-E84A (400 ng = 2.4 pmol) (A) or RPA (360 ng = 3 pmol) (B). As described under “Experimental Procedures,” immunodetection and autoradiography were used to assess binding of the protein in solution to the immobilized protein on the membrane. The amounts of RPA bound to immobilized WRN (indicated below corresponding spots in B) were determined by comparison to an RPA standard (50 fmol) spotted on each membrane.