Drosophila eIF4E paralogs: a paradigm of functional divergence

A cardinal factor in the regulation of mRNA life and function is the cap-binding protein eIF4E. eIF4E promotes the recruitment of mRNA to the ribosome during the initiation step of translation, but other activities have been described, including mRNA processing, export, and storage. To perform these functions, eIF4E must associate with the mRNA cap and a number of different eIF4E-interacting proteins (4E-IPs). Thus, eIF4E has evolved as a key interphase between RNA metabolism, gene expression, and development. In Drosophila melanogaster seven genes encode eight eIF4E cognate proteins that have functionally diverged to perform different activities. We review the structure, interactors, biochemistry, and activities of the Drosophila eIF4E paralogs, which represent a paradigm of divergence during metazoan development.