Localization, structure and expression of the gene for translation initiation factor eIF-4E from Drosophila melanogaster.

Drosophila melanogaster contains a single copy of the gene encoding translation eukaryotic initiation factor eIF-4E, which maps in the 67A2B1 region of chromosome 3L. A genomic clone containing the entire eIF-4E gene was isolated and sequenced. Comparison of this sequence with a cDNA previously obtained in our laboratory and 5'-RACE analysis revealed the existence of three mRNAs that are generated by alternative splicing of a primary transcript. All of them have different 5' untranslated leader regions. Two of the mRNAs encode the same eIF-4E polypeptide, whose sequence has been deduced from the cDNA clone. The third mRNA species contains a new open reading frame, possibly encoding another isoform of eIF-4E, which is very similar in size to the other but has a different N-terminal sequence. Several sequences which may be involved in the regulation of transcription initiation of the eIF-4E gene, except for a consensus TATA box, were found upstream of the putative transcription initiation sites. Expression of the eIF-4E gene is spatially and temporally controlled during embryonic development. It is ubiquitously expressed during embryogenesis but transcripts preferentially accumulate in certain tissues, particularly in the pole cells, at different developmental stages.