This tRNA-guanine transglycosylase (tgt) catalyzes an exchange for the guanine base at position 34 of many tRNAs; this nucleotide is subsequently modified to queuosine. The Archaea have a closely related enzyme that catalyzes a base exchange for guanine at position 15 in some tRNAs, a site that is subsequently converted to the archaeal-specific modified base archaeosine (7-formamidino-7-deazaguanosine), while Archaeoglobus fulgidus has both enzymes. [Protein synthesis, tRNA and rRNA base modification]
Jiyao W et al.(2023). "The conserved domain database in 2023.",