RAE1 is a shuttling mRNA export factor that binds to a GLEBS-like NUP98 motif at the nuclear pore complex through multiple domains

Gle2p is implicated in nuclear export of poly(A)(+) RNA and nuclear pore co mplex (NPC) structure and distribution in Saccharomyces cerevisiae. Gle2p i s anchored at the nuclear envelope (NE) via a short Gle2p-binding motif wit hin Nup116p called GLEBS, The molecular mechanism by which Gle2p and the Gl e2p-Nup116p interaction function in mRNA export is unknown, Here we show th at RAE1, the mammalian homologue of Gle2p, binds to a GLEBS-like NUP98 moti f at the NPC through multiple domains that include WD-repeats and a COOH-te rminal non-WD-repeat extension. This interaction is direct, as evidenced by in vitro binding studies and chemical cross-linking. Microinjection experi ments performed in Xeniopus laevis oocytes demonstrate that RAE1 shuttles b etween the nucleus and the cytoplasm and is exported from the nude us in a temperature-dependent and RanGTP-independent manner. Docking of RAE1 to the NE is highly dependent on new mRNA synthesis. Overexpression of the GLEBS- like motif also inhibits NE binding of RAE1 and induces nuclear accumulatio n of poly(A)(+) RNA. Both effects are abrogated either by the introduction of point mutations in the GLEBS-like motif or by overexpression of RAE1, in dicating a direct role for RAE1 and the NUP98-RAE1 interaction in mRNA expo rt. Together, our data suggest that RAE1 is a shuttling transport factor th at directly contributes to nuclear export of mRNAs through its ability to a nchor to a specific NUP98 motif at the NPC.