Fig. 2
rbFOX1 binds to expanded CCUG RNA repeats. a Left panel, gel-shift assays of 0, 0.1, 0.3, 1, 3, 10, 30, and 100 nM of purified recombinant GST-rbFOX1 with 10 pM (3000 CPM) of uniformly [αP32] internally labeled in vitro transcribed RNAs containing either 10 CUG or CCUG repeats. Right panel, gel-shift quantification. b Gel-shift as in a but with purified recombinant GST-MBNL1∆101. c Alignment of the UGCAUGC consensus RNA binding site for rbFOX1 with expanded CCUG repeats that constitute the DM2 mutation. d Model of rbFOX1 RRM bound to UGCCUGC. RNA is shown in stick representation (yellow) and potential hydrogen bonds in dashed lines (purple). e Magnification of d showing that guanine 2 and cytosine 4 form a non-Watson-Crick base pair, in an analogous way to guanine 2 and adenine 4 in rbFOX1 RRM bound to UGCAUGU described previously (pdb 2ERR)49. Error bars indicate s.e.m. of five independent experiments
