Figure 1.
Secondary structures of constructs of the 3′ splice site region of segment 7 mRNA. A red arrowhead denotes the splice site. (a) Pseudoknot and hairpin conformations from ref (15). The SF2/ASF exonic splicing enhancer binding site is colored green and a polypyrimidine tract blue.15 Numbers in brackets correspond to numbering of residues of the 39 nt hairpin studied with NMR. (b) The 39 nt hairpin studied with NMR. (c) The 11 nt hairpin mimic. (d) The 19 nt duplex model containing the 2 nt × 2 nt internal loop. The U14 residue in the 39-mer was substituted with a cytidine to stabilize formation of the target heterodimer over a homodimer.