Involved in the assembly or stability of mitochondrial NADH:ubiquinone oxidoreductase complex (complex I) (PubMed:16507593, PubMed:20406883). Acts as an arginine methyltransferase and probably acts by mediating arginine methylation of ndufs2 (By similarity). L-arginyl-[protein] + 2 S-adenosyl-L-methionine = 2 H(+) + N(omega),N(omega)'-dimethyl-L-arginyl-[protein] + 2 S-adenosyl-L-homocysteine Homodimer (PubMed:20406883). Interacts with ndufs2 (PubMed:20406883). High level of expression at the vegetative stage and the first hours of development. Cells show pleiotropic defects. Cell size, growth rate, phagocytosis and macropinocytosis are affected. During development, cells show an enhanced tendency to remain at the slug stage, and spore viability are compromised. Belongs to the NDUFAF7 family.