Figure 1.

Details of the human telomerase RNA pseudoknot. (a) Secondary structure diagrams of the minimal pseudoknot motif in a partially unfolded (hairpin) conformation and a folded (pseudoknot) conformation. The GC→AG mutation at the orange nucleotides in the pseudoknot region corresponds to the genetic disorder dyskeratosis congenita. Green (Cy3) and red (Cy5) stars indicate the location of two fluorophores, where the sizes of the stars reflect fluorescence resonance energy transfer (FRET) efficiency between the two dyes and the black vertical bar represents the ligation site. (b) Model solution structure of the minimal pseudoknot motif, with the same color scheme as the secondary structure diagram. (c) Schematic equilibrium between the pseudoknot and hairpin conformations.