Figure 4.

Tertiary structure elements are unfolded in the absence of Mss116p. (A) Representative gel showing the accessibility of nucleotides in the c-c1-c2 three-way junction, which harbors the θ, λ, ε′ and β elements forming long-range tertiary contacts with distinct regions of the intron, in the wt and mss116-knockout strain. Lanes are designated as in Figure 1; symbol code as in Figure 3. The normalized plot derived from this gel is shown (Suppl. Fig. 4C). (B) Representative gel showing the accessibility of residues in stem d3 including the exon binding site 1 (EBS1) and the α′ element, which forms an intra-domain contact with the closing loop of stem b. Lanes are designated as in Figure 1; symbol code as in Figure 3. The normalized plot derived from this gel is shown Supplementary Figure 4D.