IUBMB Enzyme Nomenclature


Accepted name: tRNA (cytosine34-C5)-methyltransferase

Reaction: S-adenosyl-L-methionine + cytosine34 in tRNA precursor = S-adenosyl-L-homocysteine + 5-methylcytosine34 in tRNA precursor

Other name(s): hTrm4 Mtase; hTrm4 methyltransferase; hTrm4 (gene name); tRNA:m5C-methyltransferase (ambiguous)

Systematic name: S-adenosyl-L-methionine:tRNA (cytosine34-C5)-methyltransferase

Comments: The human enzyme is specific for C5-methylation of cytosine34 in tRNA precursors. The intron in the human pre-tRNALeu(CAA) is indispensable for the C5-methylation of cytosine in the first position of the anticodon. It is not able to form 5-methylcytosine at positions 48 and 49 of human and yeast tRNA precursors [1].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:


1. Brzezicha, B., Schmidt, M., Makalowska, I., Jarmolowski, A., Pienkowska, J. and Szweykowska-Kulinska, Z. Identification of human tRNA:m5C methyltransferase catalysing intron-dependent m5C formation in the first position of the anticodon of the pre-tRNA Leu (CAA). Nucleic Acids Res. 34 (2006) 6034-6043. [PMID: 17071714]

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