tRNA modification wybutosine biosynthetic process yW biosynthesis Note that wybutosine is a hypermodified G-residue, formerly called the Y-base, and its derivatives are exclusively found at position 37 (anticodon loop) of tRNAPhe. biological_process The chemical reactions and pathways resulting in the formation of wybutosine, 3H-imidazo[1,2-alpha]purine-7-butanoic acid, 4,9-dihydro- alpha-[(methoxycarbonyl)amino]- 4,6-dimethyl-9-oxo- 3-beta-D-ribofuranosyl methyl ester, a modified nucleoside found in some tRNA molecules. GO:0031591 yW biosynthetic process glycosyl compound biosynthetic process