Comparison of consensus sequences in the human members of the fragile X gene family. (a) Protein sequence alignment of the RGG boxes of FMRP, FXR1P and FXR2P. The consensus sequence is indicated in dark blue and differences are highlighted in light blue. We used the RGG-box consensus motif determined by Burd and Dreyfuss  and the alignment of the three proteins generated by Zhang et al. . Other possible RGG motifs for FXR1P and FXR2P are boxed. (b, c) Transcript sequence comparison of the purine-rich region between FMR1 and the autosomal paralogs FXR1 and FXR2. Guanines conserved between human, mouse and rat FMR1 genes are indicated in dark blue; some of these are not conserved in FXR1 and FXR2 (highlighted in light blue). The sequences in (c) continue from (b).