Fig. 7. Surface representation of the σ3 dimer. Regions of positive electrostatic potential are shown in blue; regions of negative potential in red. The orientation of the top molecule in (A) is identical to the orientation in Figure 1A, and (B) is a view of the molecule rotated 180° about the long axis. Just left and right of center in (A) are positively charged patches in each monomer surrounding Lys293 (arrows), which we propose are the sites for binding dsRNA. Scale bar, 10 Å.