RNA methyltransferase that methylates tRNAs. Methylates cytosine to 5-methylcytosine (m5C) at position 34 of intron-containing tRNA(Leu)(CAA) precursors. Required for short-term memory. cytidine(34) in tRNA precursor + S-adenosyl-L-methionine = 5-methylcytidine(34) in tRNA precursor + H(+) + S-adenosyl-L-homocysteine Ubiquitously expressed during embryonic development. Some enrichment is observed in the proventriculus area of the foregut and in the hindgut. Expressed maternally and zygotically. Expressed during embryonic development. Belongs to the class I-like SAM-binding methyltransferase superfamily. RsmB/NOP family. TRM4 subfamily.