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Nuclear export of single large ribosomal subunits and mRNA particle

This talk focuses on RNA export studied in vivo by single particle tracking and super resolution microscopy. (1) We analysed the export kinetics of single large ribosomal subunits (pre-60S particles) through single NPCs in human cells. Successful export has a single rate limiting step presumably corresponding to the release of the particle from the centre of the pore. Only about 1/3 of attempted export events are successful. Unsuccessful export terminates within the nuclear basket. (2) It is well known that the RNA helicase DDX19 (Dbp5 in yeast) plays a key role in establishing the directionality of mRNA export. We studied the DDX19 reaction cycle using a range of mutants in single particle tracking experiments of this protein and mRNA particles. From our data we yield a model of the DDX19 reaction cycle at the NPC.