Figure 6.

In vitro genetic analysis of the conserved core region of the two group IC3 intron ribozymes. (A) The secondary structure of the coreMix variant pool for the in vitro selection. Mixed nucleotides were introduced at the 14 positions indicated by R(A/G), S(G/C) or Y(C/U) in the core region. (B) The 3′-splice site-specific hydrolysis activity of the pool at each round of the selection cycle. Uniformly ³²P-labeled precursor ribozymes from each round were incubated for 90 min. The activities of the sP2 form of coreSyn-4 (not detected) or coreAzo-4 (gray bar) are also indicated.