Involved in the assembly of mitochondrial NADH:ubiquinone oxidoreductase complex (complex I, MT-ND1) at early stages (PubMed:23536703). Probably acts as an arginine hydroxylase (By similarity). May also have methyltransferase activity. Defects in development due to mitochondrial NADH:ubiquinone oxidoreductase complex (complex I, MT-ND1) deficiency (PubMed:23536703). Increased autophagy (PubMed:23536703). Belongs to the methyltransferase superfamily.