Cleaves the 2′-5′ phosphodiester linkage at the branch point of excised lariat intron RNA and converts them into linear molecules that can be subsequently degraded, thereby facilitating ribonucleotide turnover (PubMed:10982890, PubMed:16232320, PubMed:2435736). Linked to its role in pre-mRNA processing mechanism, may also participate in retrovirus replication via an RNA lariat intermediate in cDNA synthesis and have an antiviral cell-intrinsic defense function in the brainstem (PubMed:16232320, PubMed:29474921).
