Structural and functional control of the eukaryotic mRNA decapping machinery

► Decapping inactivates translation initiation and initiates 5′-to-3′ decay of mRNA. ► The Dcp1-Dcp2 decapping complex is widely conserved among eukaryotes. ► An open-to-closed transition controls the activity of the Dcp1-Dcp2 complex. ► Multiple enhancers of decapping promote decapping by different mechanisms. ► mRNAs that accumulate with decapping complexes can assemble into P bodies.