Fig. 5

a Dimeric SoxE TFBS, as predicted by JASPAR (outlined in red), are present in the conserved sequence of peak5. b Schematic of plasmids used in the experiment. Mutations to SoxE TFBS were made in the context of the full-length WT peak5 plasmid. c Five out of six nucleotides for each motif were mutated. d Quantification of the percentage of categorizable EGFP + embryos exhibiting NC, KA, both NC, and KA, or ectopic expression in screened WT peak5 (n = 45) and peak5_SoxEmut (n = 31) injected embryos. NC neural crest, KA Kolmer–Agduhr neurons. p-value = 0.0324, Fisher’s exact test. Injection of crestin:mCherry simply served as a positive injection control in this experiment. ecrestin:mch expression in an embryo injected with WT peak 5 and crestin:mch. fWT peak5 is strongly active in neural crest in F0 mosaics at 1 dpf. gWT peak5 is strongly active in neural crest-derived cells and KA neurons at 2 dpf. hcrestin:mch expression in an embryo injected with peak5_SoxEmut and crestin:mch. ipeak5_SoxEmut is not active in the neural crest in F0 mosaics, but j is active in KA neurons. Arrowheads indicate KA neurons. k–k′ Stable transgenic peak5_SoxEmut lines exhibit peak5 activity in KA neurons, but do not exhibit labeling in posterior premigratory neural crest cells. l Adult stable transgenic lines do not exhibit peak5 activity in barbel peripheral nerves. m, n Tumors that develop in Tg(peak5_SoxEmut:EGFP) lines are EGFP negative.