Cup puts a lid and a handle on mRNA

Using a biochemical approach to a longstanding problem in Drosophila genetics, Wilhelm et al. (page 1197) have identified a novel protein that links translational repression to mRNA localization and also uncovered a surprisingly specific localization pattern for a ubiquitous translation factor.

Polarized cells often rely on mRNA localization to restrict protein distribution. During fly oocyte development, for example, oskar mRNA moves from the posterior end of the oocyte to an anterior position, then back to the posterior end before being translated. As Oskar expression determines posterior patterning and germline establishment, the mRNA must be repressed until it reaches its final position. Something must coordinate the localization and translational repression of the message, but genetic studies have only found mutants that affected localization or repression, not both.

Wilhelm et al. now identify...