Cyclin D1 (red, left) but not GAPDH (red, right) is found in nuclear bodies with eIF4E (green).
The promiscuous function of the eIF4E translation initiation factor is to bring all mRNAs to the ribosome. Although transcript sequences vary greatly, eIF4E recognizes them all by their ubiquitous 5′ cap structure. A less well-understood function of eIF4E, however, lies in its ability to export specific transcripts from the nucleus, thus increasing the amount available for translation. Only two transcripts have so far been shown to be exported by eIF4E—cyclin D1 and ornithine decarboxylase (ODC).
The new results map eIF4E's export selectivity to a 100-bp sequence in the cyclin D1 3′ UTR, which the authors call the 4E-SE. eIF4E's cap-binding ability was also required for export....
