Fig. 1. Comparison of human FXR1P and the zebrafish Fxr-protein family. Identical residues are shaded in black, and conserved substitutions in grey. The following functional domains are indicated: the nuclear localization signal (NLS), the two KH1 RNA-binding domains (KH1), the nuclear export signal (NES), the conserved casein kinase II phosphorylation site found in Drosophila Fmrp (CKII), the region containing the RNA interaction RGG box (RGG) and two nucleolar targeting signals (NoS1 and NoS2). The boxed region of mouse and zebrafish Fxr1p that contains the second NoS indicates the alternatively spliced exon 15 of Fxr1p. The epitope of the affinity-purified anti-Fxr1p antibody Affi5 is depicted with the synthetic peptide.