IUBMB Enzyme Nomenclature


Accepted name: tRNA-guanosine34 queuine transglycosylase

Reaction: guanine34 in tRNA + queuine = queuine34 in tRNA + guanine

For diagram of reaction click here

Glossary: queuine = base Q = 2-amino-5-({[(1S,4S,5R)-4,5-dihydroxycyclopent-2-en-1-yl]amino}methyl)-1,7-dihydropyrrolo[3,2-e]pyrimidin-4-one

Other name(s): QTRT1 (gene name); QTRT2 (gene name); TGT (ambiguous); guanine insertion enzyme (ambiguous); tRNA transglycosylase (ambiguous); Q-insertase (ambiguous); queuine34 transfer ribonucleate ribosyltransferase; transfer ribonucleate glycosyltransferase (ambiguous); tRNA guanine34 transglycosidase (ambiguous); queuine tRNA-ribosyltransferase; [tRNA]-guanine34:queuine tRNA-D-ribosyltransferase; transfer ribonucleic acid guanine34 transglycosylase (ambiguous)

Systematic name: tRNA-guanosine34:queuine tRNA-D-ribosyltransferase

Comments: Certain prokaryotic and eukaryotic tRNAs contain the modified base queuine at position 34. In eukaryotes and a small number of prokaryotes queuine is salvaged and incorporated into tRNA directly via a base-exchange reaction, replacing guanine. cf. EC, tRNA-guanosine34 preQ1 transglycosylase.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Howes, N.K. and Farkas, W.R. Studies with a homogeneous enzyme from rabbit erythrocytes catalyzing the insertion of guanine into tRNA. J. Biol. Chem. 253 (1978) 9082-9087. [PMID: 721832]

2. Shindo-Okada, N., Okada, N., Ohgi, T., Goto, T. and Nishimura, S. Transfer ribonucleic acid guanine transglycosylase isolated from rat liver. Biochemistry 19 (1980) 395-400. [PMID: 6986171]

3. Boland, C., Hayes, P., Santa-Maria, I., Nishimura, S. and Kelly, V.P. Queuosine formation in eukaryotic tRNA occurs via a mitochondria-localized heteromeric transglycosylase. J. Biol. Chem. 284 (2009) 18218-18227. [PMID: 19414587]

4. Yuan, Y., Zallot, R., Grove, T.L., Payan, D.J., Martin-Verstraete, I., Sepic, S., Balamkundu, S., Neelakandan, R., Gadi, V.K., Liu, C.F., Swairjo, M.A., Dedon, P.C., Almo, S.C., Gerlt, J.A. and de Crecy-Lagard, V. Discovery of novel bacterial queuine salvage enzymes and pathways in human pathogens. Proc. Natl. Acad. Sci. USA 116 (2019) 19126-19135. [PMID: 31481610]

[EC created 2020 (EC created 1984, modified 2007, modified 2012, part transferred 2020 to EC]

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