Enables tRNA (cytosine-5-)-methyltransferase activity. Involved in tRNA stabilization. Acts upstream of or within tRNA methylation. Predicted to be located in cytoplasm. Is expressed in several structures, including central nervous system; olfactory epithelium; reproductive system; thymus; and thyroid gland. Orthologous to human TRDMT1 (tRNA aspartic acid methyltransferase 1). [provided by Alliance of Genome Resources, Apr 2022]