FIGURE 1.
Secondary structures of hammerheads arranged to resemble the crystal structure. The catalytic core residues are indicated by open letters. (A) The rapidly cleaving sequence derived from the satellite RNA of tobacco ringspot virus studied by Khvorova et al. (2003). The proposed tertiary interaction occurs between the loops at the ends of Stems 1 and 2. (B) The 55-nucleotide minimal hammerhead derived from the virusoid of leucerne transient streak virus identified by Forster and Symons. Hammerheads formed from two oligonucleotides described by (C) Uhlenbeck (1987) and (D) Haseloff and Gerlach (1988).
