Plays an important role in the processing of non-canonical mitochondrial mRNA precursors. Found in a complex with GRSF1, DDX28, DHX30 and FASTKD2. Associates with the 12S mitochondrial rRNA (12S mt-rRNA). Localizes to mitochondrial RNA granules found in close proximity to the mitochondrial nucleoids. Expression detected in spleen, testis, colon, heart, smooth muscle, kidney, brain, lung, liver, brown and white adipose tissue. Belongs to the FAST kinase family. Extended N-terminus. Extended N-terminus.