Me31B silences translation of oocyte-localizing RNAs through the formationof cytoplasmic RNP complex during Drosophila oogenesis

Embryonic patterning in Drosophila is regulated by maternal factors. Many s uch factors become localized as mRNAs within the oocyte during oogenesis an d are translated in a spatio-temporally regulated manner. These processes a re controlled by trans-acting proteins, which bind to the target RNAs to fo rm a ribonucleoprotein (RNP) complex. We report that a DEAD-box protein, Me 31B, forms a cytoplasmic RNP complex with oocyte-localizing RNAs and Exuper antia, a protein involved in RNA localization. During early oogenesis, loss of Me31B causes premature translation of oocyte-localizing RNAs within nur se cells, without affecting their transport to the oocyte. These results su ggest that Me31B mediates translational silencing of RNAs during their tran sport to the oocyte. Our data provide evidence that RNA transport and trans lational control are linked through the assembly of RNP complex.