FIG. 3.

The ORF 73 amino-terminal arginine-rich domains are required for p32 binding. (a) A further series of amino-terminal ORF 73 deletions were expressed as GST fusion proteins. (b) Control GST alone, GST-73N, GST-73ΔNLS1, GST-73ΔNLS2, and GST-73ΔNLS1+2 were expressed in E. coli and purified from crude lysate by incubation with glutathione-Sepharose 4B affinity beads. Protein extracts of untransfected cells were incubated with GST or GST-ORF 73 amino deletion proteins. (i) Bound proteins were resolved by SDS-PAGE (12% polyacrylamide), and p32 was detected by Western blotting using p32 antiserum. (ii) To confirm the expression of GST and GST-ORF 73 amino deletion fusion proteins, Western blot analysis was performed using a mouse monoclonal GST antibody.