The function of METTL6 (methyltransferase 6, tRNA N3-cytidine, Ensembl gene identifier ENSG00000206562) is as follows. 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) (PubMed:32923617, PubMed:34268557, PubMed:34862464, PubMed:34922197). Interaction with SARS1/SerRS is required for N(3)- methylcytidine methylation (PubMed:34268557). {ECO:0000269|PubMed:32923617, ECO:0000269|PubMed:34268557, ECO:0000269|PubMed:34862464, ECO:0000269|PubMed:34922197}.