QTRT1 also known as queuine tRNA-ribosyltransferase. QTRT1 interacts with QTRTD1 to form an active queuine tRNA-ribosyltransferase. This enzyme exchanges queuine for the guanine at the wobble position of tRNAs with GUN anticodons (tRNA-Asp, -Asn, -His and -Tyr), thereby forming the hypermodified nucleoside queuosine (Q) (7-(((4,5-cis-dihydroxy-2-cyclopenten-1-yl)amino)methyl)-7-deazaguanosine). Recombinant QTRT1 was expressed in E.coli and purified by using conventional chromatography techniques.