Fig. 6.

Motifs found in the screen regulate endogenous 3′UTRs. Human 3′UTRs containing conserved instances of motifs found from the screen were identified. Sequences from human, mouse, rat, and dog 3′UTRs were aligned, and 3′UTRs which contained an intact and orthologous instance of the 8mer in the four species were considered. Fragments of ~500 nt of human 3′UTRs containing conserved motifs were inserted into luciferase reporter constructs. The candidate motif was mutated at three positions to create a negative control, reasoning that three sequence changes were sufficient to ablate potential function of the original motif. The luciferase activity of constructs containing the intact motif were normalized to the construct with a mutated motif. Reporter data are plotted as the geometric mean of relative luminescence (y-axis) of reporter constructs normalized to those with mutated sites; error bars indicate 68 % of the data. Significance was determined by a two-sided Wilcoxon rank sum test, n = 6; *p < 0.05, **p < 0.005 after Bonferonni correction