Degrades RNA oligonucleotides with a length of 5 nucleotides in a 3'- to 5'-direction. Less active on shorter RNA oligonucleotides and on those with a length of 24 nucleotides. Prefers RNA oligonucleotides containing adenines rather than cytosines. Optimum pH is 7.5-8.0. No visible phenotype. Cells show normal growth.