Nuclear export as a key arbiter of “mRNA identity” in eukaryotes

► Eukaryotes have elevated levels of spurious transcription from intergenic regions. ► Eukaryotes must ensure that only protein-coding mRNAs undergo nuclear export. ► Through a coupling network, export factors evaluate mRNA identity features. ► The signal sequence coding region is an mRNA identity element for nuclear export. ► Gradients of GC-content may also serve as general mRNA identity features.