Figure 5.

Correlation of C1'–C1' distances for the 2b•2n and 3b•3n basepairs of known k-turn structures. The two C1'–C1' have been measured for each k-turn structure and plotted as shown. N3 structures are plotted in blue, N1 structures in red. Note that the two groups form two distinct clusters of points such that the N3 structures evidently are associated with a narrower NC helix. The exceptional HmKt-7 structure within the ribosome is plotted in green using an open circle. An additional plot identifying each k-turn and showing its 3b,3n sequence is shown in Supplementary Figure S6.