The enzyme is involved in the biosynthesis of hypermodified tricyclic bases found at position 37 of certain tRNAs. These modifications are important for translational reading-frame maintenance. The enzyme is found in all eukaryotes and in some archaea, but not in bacteria. The eukaryotic enzyme is involved in the biosynthesis of wybutosine.
in DELTATYW3 strain, tRNAPhe has two wybutosine intermediates, 7-(3-amino-3-carboxypropyl)-4-demethylwyosine37 (yW-86) and 4-demethylwyosine37 (yW-14). Recombinant TYW3 clearly methylated 7-(3-amino-3-carboxypropyl)-4-demethylwyosine37 in tRNA to yield 7-(3-amino-3-carboxypropyl)-4-methylwyosine37 in tRNA in S-adenosyl-L-methionine-dependent manner. 4-Demethylwyosine37 is not methylated by TYW3