Figure 2: (a) Normalized SHAPE-reactivity profile of the RPS12 pre-mRNA in dilute solvent conditions. Black: low (<0.35 SU); orange: medium (0.35 ≤ SU < 0.8); red: high (≥0.8) normalized SHAPE reactivities. SU: SHAPE-unit. nt: nucleotide(s). (b) Difference () SHAPE-reactivity profiles of the RPS12 transcript at crowded and/or Mg2+-free solvent conditions. Green: nt-positions with increased SHAPE reactivities (dark green: 0.35 ≤ SU ≤ 2; light green: 0.2 ≤ SU < 0.35). Blue: nt-positions with decreased SHAPE reactivities (light blue: −0.2 ≥ SU > −0.35; dark blue: −0.35 ≤ SU ≤ −0.2). Black: nonresponsive nt-positions (−0.2 ≤ SU ≥ 0.2).