:TRNA:m4X modification enzyme

{{Infobox enzyme

| Name = TRNA:m4X modification enzyme

| EC_number = 2.1.1.225

| CAS_number =

| GO_code =

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TRNA:m4X modification enzyme ({{EC number|2.1.1.225}}, TRM13, Trm13p, tRNA:Xm4 modification enzyme) is an enzyme with systematic name S-adenosyl-L-methionine:tRNAPro/His/Gly(GCC) (cytidine/adenosine4-2'-O)-methyltransferase.{{cite journal | vauthors = Wilkinson ML, Crary SM, Jackman JE, Grayhack EJ, Phizicky EM | title = The 2'-O-methyltransferase responsible for modification of yeast tRNA at position 4 | journal = RNA | volume = 13 | issue = 3 | pages = 404–13 | date = March 2007 | pmid = 17242307 | pmc = 1800514 | doi = 10.1261/rna.399607 }} This enzyme catalyses the following chemical reaction

: (1) S-adenosyl-L-methionine + cytidine⁴ in tRNAPro $\backslash rightleftharpoons$ S-adenosyl-L-homocysteine + 2'-O-methylcytidine⁴ in tRNAPro

: (2) S-adenosyl-L-methionine + cytidine⁴ in tRNAGly(GCC) $\backslash rightleftharpoons$ S-adenosyl-L-homocysteine + 2'-O-methylcytidine⁴ in tRNAGly(GCC)

: (3) S-adenosyl-L-methionine + adenosine⁴ in tRNAHis $\backslash rightleftharpoons$ S-adenosyl-L-homocysteine + 2'-O-methyladenosine⁴ in tRNAHis

The enzyme from Saccharomyces cerevisiae 2'-O-methylates cytidine⁴ in tRNAPro and tRNAGly(GCC), and adenosine⁴ in tRNAHis.