Nuclear export of mRNA: from the site of transcription to the cytoplasm.

Cellular mRNAs are produced in the nucleus and must be exported to the cytoplasm to allow for their translation into proteins. Recruitment of export factors to nascent mRNA starts cotranscriptionally and involves elaborate systems of quality control. Correctly processed mRNAs are committed for export in the form of large ribonucleoprotein complexes (mRNPs). Translocation of mRNPs through the nuclear pore complex (NPC) is mediated by a conserved heterodimeric transport receptor (NXF1/p15 in metazoa and Mex67p/Mtr2p in yeast) that bridges the interaction between the mRNP and the NPC. In this review, we describe the cis- and trans-requirements for mRNA export as well as the different mechanisms of recruiting export factors to mRNPs. We also discuss the significance of linking mRNA export with both downstream and upstream events in gene expression.