FIG. 7.

3BCD and its cleavage products: substrates and stimulatory factors for uridylylation. Large ovals represent the viral protein domains; wavy lines represent polypeptide chains. The cre RNA is predicted to have a stem-loop structure and is shown in gray. The purple and yellow rectangles represent the D-D and D-C interfaces, respectively, as they are seen in the 3CD crystal structure (shown in Fig. 5). The binding of additional copies of the 3C and/or 3D domains and the involvement of additional interfaces cannot be ruled out.