The RNA export factor Mex67 functions as a mobile nucleoporin
The mRNA export receptor Mex67 mediates the selective export of large RNA-protein particles from the nucleus to the cytoplasm. In "JCB", Carina Derrer et al. from the Weis/Dultz group now use quantitative fluorescence microscopy techniques to challenge current models of mRNA export.
The RNA export factor Mex67 is essential for the transport of mRNA through the nuclear pore complex (NPC) in yeast. Current models postulate that Mex67 is loaded onto mRNA in the nucleus and upon NPC translocation is released in the cytoplasm. Derrer et al. now used quantitative fluorescence microscopy techniques in live budding yeast cells to investigate how Mex67 facilitates mRNA export. Surprisingly, they observe little binding of Mex67 to cargo in the nucleus and no evidence for release of Mex67 to the cytoplasm upon completion of the export process. This suggests a novel model for mRNA export where Mex67 function is restricted to the nuclear pore complex. Indeed, the group around Karsten Weis and Elisa Dultz could demonstrate that Mex67 can still perform its essential function in mRNA export when stably tethered to the nuclear pore complex.
Link to the publication in external pageJournal of Cell Biology