exonuclease activity exoribonuclease activity Catalysis of the sequential cleavage of mononucleotides from a free 5' or 3' terminus of an RNA molecule. Reactome:REACT_109605 Reactome:REACT_109680 Reactome:REACT_20556 Reactome:REACT_29104 Reactome:REACT_32104 Reactome:REACT_78260 Reactome:REACT_79364 Reactome:REACT_79874 Reactome:REACT_87278 Reactome:REACT_88925 Reactome:REACT_90233 Reactome:REACT_94168 Reactome:REACT_99687 Reactome:REACT_99790 ribonuclease activity