A graveyard for mRNA

Another day, another organelle. Cytoplasmic foci of various mRNA processing enzymes have now been confirmed by Ujwal Sheth and Roy Parker (University of Arizona, Tucson, AZ) as functional sites for degrading mRNA. But that confirmation has led to a host of questions about the origins and range of functions of these processing bodies (P bodies).

Sheth and Parker found that mRNA decapping enzymes, activators of decapping, and an mRNA nuclease all clustered in two to three P bodies per budding yeast cell. The P bodies melted away when mRNA turnover was inhibited before decapping (by inhibiting deadenylation), but proliferated when the inhibition was at or after the decapping step. Finally, a decay intermediate was localized to P bodies.

The range of reactions occurring in the P bodies remains to be explored, as does the significance...