Catalysis of the removal of the cap from an unmethylated 5'-end capped RNA resulting in the release of the entire cap structure (GpppN) and a 5' monophosphorylated RNA.
ribonuclease [poly-(U)-specific] activity
ribonuclease III activity +
ribonuclease IV activity
ribonuclease IX activity
ribonuclease M5 activity
ribonuclease P activity
ribonuclease P4 activity
RNA lariat debranching enzyme activity
RNA-(apurinic or apyrimidinic site) endonuclease activity