Required for the export of mRNAs containing poly(A) tails from the nucleus into the cytoplasm. Probable component of the nuclear pore complex (NPC). Interacts with nuclear export protein NXF1. Interacts with GLE1. Able to form a heterotrimer with NUP155 and GLE1 in vitro (By similarity). Interacts with XPO1 (By similarity). Excluded from the nucleolus. The FG repeats are interaction sites for karyopherins (importins, exportins) and form probably an affinity gradient, guiding the transport proteins unidirectionally with their cargo through the NPC. O-glycosylated.