FIGURE 2.
A proposed mechanism (A–E) for the involvement of the putative pseudoknots PK1, PK3, and PK4 in the regulation of −1 PRF in HIV-1. The sequence of strain HXB2 is used as an example. The secondary structures of the pseudoknots are the same as in Figure 1, although the drawings appear different. The slippery sequence UUUUUUA is highlighted in red. Small bars associated with the residues indicate that the residues are or were participating in base-pairing interactions.
