Mechanisms of Messenger RNA Packaging and Export

The packaging and export of messenger RNA (mRNA) are essential cellular pathways that bridge the nuclear and cytoplasmic phases of eukaryotic gene expression. During their nuclear maturation, mRNAs are packaged by proteins into mRNA ribonucleoproteins (mRNPs). Other proteins then assist in the export of mRNPs into the cytoplasm for translation. Together, these proteins play critical roles in compacting the mRNA, defining mRNA identity, preventing unwanted interactions, and orchestrating mRNA transport through the nuclear pore complex (NPC). Here, we review decades of genetics and biochemistry alongside recent structural and functional insights and outline a general framework for the late stages of nuclear mRNA biogenesis and export. We also highlight open questions, including the mechanisms of mRNP packaging, mRNP export through the NPC, and the regulation, quality control, and exploitation of the pathway.