Decapping and exoribonuclease protein (DXO)

Ribonuclease that specifically degrades pre-mRNAs with a faulty 5' end cap and is a part of a pre-mRNA capping quality control. Has decapping, pyrophosphohydrolase and 5'-3' exonuclease activities.

Has decapping activity toward immaculate 5' end cap mRNAs like unmethylated 5' end-capped RNA to release GpppN and 5' end monophosphate RNA. The 5' end monophosphate RNA is then degraded by the 5'-3' exoribonuclease activity, enabling this enzyme to decap and hamper incompletely capped mRNAs.