3'-5' RNA exonuclease which cleaves in situ on specific transcripts in both nucleus and mitochondrion. Involved in regulating spatially segregated organellar RNA processing, acts as a coordinator of nucleo-mitochondrial crosstalk (PubMed:31081026). In nucleolus, processes pre-ribosomal RNA involved in ribosome assembly and alters cytoplasmic translation. In mitochondrial matrix, processes 3'-termini of the mito-ribosomal and messenger RNAs and controls translation of mitochondrial proteins (Probable). {ECO:0000269|PubMed:31081026, ECO:0000305|PubMed:31081026}. This is the function of Ensembl gene identifier ENSG00000139637 (MYG1, MYG1 exonuclease).