Ribonuclease that plays an essential role in innate immune response by recognizing and degrading RNAs from microbial pathogens that are subsequently sensed by TLR8. Cleaves preferentially single-stranded RNA molecules between purine and uridine residues, which critically contributes to the supply of catabolic uridine and the generation of purine-2',3'-cyclophosphate-terminated oligoribonucleotides . In turn, RNase T2 degradation products promote the RNA-dependent activation of TLR8 . Plays also a key role in degradation of mitochondrial RNA and processing of non-coding RNA imported from the cytosol into mitochondria . Participates as well in degradation of mitochondrion-associated cytosolic rRNAs.