S-adenosyl-L-methionine-dependent methyltransferase that mediates N(3)-methylcytidine modification of residue 32 of the tRNA anticodon loop of tRNA(Ser), including tRNA(Ser)(UGA) and tRNA(Ser)(GCU) ( , ). Interaction with SARS1/SerRS is required for N(3)-methylcytidine methylation .
Subcellular locations: Cytoplasm, Nucleus