Figure 7

G4-RNA formation within 5′-UTR of ras mRNAs . (A) Sequence of 5′-UTR in the murine KRAS mRNA. The quadruplex-forming sequences (QFS) utr-1, utr-2, utr-3, utr-4 and utr-5 are boxed (strong QFS, full line; weak QFS broken line); (B) Typical CD spectra at various temperatures (from 20 to 90°C) of sequence utr2. Spectra have been collected at 20–30–40–50–60–70–80–90°C, using RNA 10 μM RNA, 50 mM Tris-HCl, pH 7.4, 100 mM KCl. The ordinate reports the CD values in mdeg. Graph below shows the CD-melting curve of the utr-2 G-quadruplex; (C) UV-vis titration of porphyrin C14 (6 μM) with quadruplex utr-2. Inset shows the fraction of bound C14 as a function of G4-RNA. The experimental points have been best fitted to a standard binding equation (Sigma Plot 11.0).