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A more recent version of this article appeared on January 1, 2008
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Submitted on March 19, 2007
Revised on September 21, 2007
Accepted on October 18, 2007
Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
Monitoring Editor: Karsten Weis
Nuclear export of mRNAs is mediated by the Tap/Nxt1 pathway. Tap moves its RNA cargo through the NPC by direct interaction with nucleoporin FG repeats. This interaction is strengthened by the formation of a Tap/Nxt1 heterodimer. We now present evidence that Tap can form a multimeric complex with itself and with other members of the NXF family. We also show that the homotypic Tap complex can interact with both Nxt1 and nucleoporins in vitro. The region mediating this oligomerization is localized to the first 187 amino acids of Tap, which overlaps with its RNA-binding domain. Removal of this domain greatly reduces the ability of Tap to bind nucleoporins in vitro and in vivo. This is the first report showing that the Tap amino terminus modulates the interaction of Tap with nucleoporins. We speculate that this mechanism has a regulatory role for RNA export independent of RNA-binding.