(A) Native gel of: MAP1B_RNA (lane 1), SC1_RNA (lane 2), MUNC_RNA (lane 3), and FMRP_RNA (lane 4) run using 0.12 mM RNA concentrations in 40 mM Tris-Acetate (pH 7.2) and 100 mM KCl (left) and 100 mM LiCl (right). (B) Fitting of a typical set of analytical ultracentrifugation data recorded for the three RNAs. Sample concentrations were 1 μM in 10 mM Tris-HCl (pH 7.4) and 150 mM KCl. (C) Summary of the observed secondary structures and multimeric state of the three RNAs studied. Appropriate symbols are used for indicating the presence of G-quartets and Watson–Crick base pairing. Monomers and dimers are indicated with one and two ovals, respectively. Plus and ampersand are used to indicate the coexistence of monomeric and dimeric species in solution and of helical and G-quartet structures. It should, however, be appreciated that the two types of secondary structures can, in principle, be formed intramolecularly or intermolecularly.
