Involved in tRNA methylation. Facilitates the recognition and targeting of tRNA(Arg)(CCU) and tRNA(Arg)(UCU) substrates for N(3)-methylcytidine modification by METTL2. Part of a complex containing tRNA(Arg) and METTL2. Interacts with tRNA(Arg)(CCU) and tRNA(Arg)(UCU). Interacts with METTL2.