FIGURE 5.

Effects of mutations that alter that terminator hairpin on regulatory activity. A, effect of point mutations in P4b or the internal loop between P4a and P4b on 2-AP-dependent regulatory activity. To the right is the secondary structure of each mutant tested. The -fold induction (FI) values are given below the graph. B, effect of extending the P4b helix to compensate for its partial disruption by the P1+8 mutation. Error bars represent the S.E. of three separate experiments. A.U., arbitrary units.