“…At this moment it is difficult to predict exactly how these factors contribute to the metabolism of mitochondrial RNAs, but at least some proteins have been reported to have a mitochondrial function. In addition to Hts1, Vas1, Ala1 and Grs1 enzymes that aminoacylate tRNAs in mitochondria (28,29,32,33), other cases include endonuclease Trz1 that participates in the processing of mitochondrial transcripts (70), Rnh1 (Ribonuclease H1, RNase H1) that cleaves RNA–DNA hybrids and has been implicated in the resolution of R-loops in mitochondria (107); a DEAH box RNA spliceosomal helicase Prp43 that has been postulated to function in mitochondria in apoptosis (108) and Jsn1, a cytoplasmic member of the Puf RNA binding family proteins that also facilitates localization of Arp2/3 to mitochondria (109). Notably, human homologs of some of these factors, namely tRNA endonuclease RNAse Z L , RNase H1 and helicase DHX15, have a dual nuclear-mitochondrial localization and a described mitochondrial function (110–113).…”