FIE3 (ftz instability element 3') element

The FIE3 (ftz instability element 3') element is an RNA element found in the 3' UTR of the fushi tarazu mRNA. The fushi tarazu gene is essential for the establishment of the Drosophila embryonic body plan. When first expressed in early embryogenesis, fushi tarazu mRNA is uniformly distributed over most of the embryo. Subsequently, fushi tarazu mRNA expression rapidly evolves into a pattern of seven stripes that encircle the embryo. The instability of fushi tarazu mRNA is probably crucial for attaining this localised pattern of expression. Experiments provide evidence for at least two destabilising elements in the fushi tarazu mRNA, one located within the 5' one-third of the mRNA and the other near the 3' end (termed FIE3 for ftz instability element 3'). The FIE3 lies within a 201-nucleotide sequence just upstream of the polyadenylation signal and can act autonomously to destabilise a heterologous mRNA. Further deletion constructs identified an essential 68-nucleotide element within the FIE3.