Regulator of mitochondrial ribosome biogenesis and translation. Binds to mitochondrial ribosomal RNAs 16S, 12S and 7S and targets NSUN4 RNA methyltransferase to the mitochondrial large ribosomal subunit (By similarity). Heterodimer with NSUN4; this interaction may be required for NSUN4 recruitment to the mitochondrial large ribosomal subunit. The MTERF repeats form a half-donut shaped, right-handed superhelix, where the concave side displays a positively charged path for nucleic acid interaction. Belongs to the mTERF family.