tRNA-guanine transglycosylase (IPR004803)

Short name: TGT

Overlapping homologous superfamilies

Family relationships



Queuine is a hypermodified base that occurs in the wobble position of the anticodon of tRNAs Asp, Asn, His and Tyr. Queuine is incorporated into tRNA via a base exchange reaction with guanine catalysed by queuine tRNA-ribosyltransferase (also known as tRNA-guanine transglycosylase). In eukaryotes, queuine is directly exchanged into tRNA while in eubacteria, a queuine precursor (preQ1) is incorporated and ultimately modified to queuine [PMID: 12697167, PMID: 16401090]. Archaea contain a closely related enzyme (IPR004804) that catalyses a base exchange of guanine for an archaeosine precursor [PMID: 10862614]. This precursor is then subsequently converted to the archaeal-specific modified base archaeosine. Some archaea, such as Archaeoglobus fulgidus, contain both these enzymes.

The eukaryotic tRNA-guanine transglycosylase exists as a heterodimer of a catalytic subunit (QTRT1) and another subunit known as queuine tRNA-ribosyltransferase domain-containing 1 (QTRTD1), whereas the eubacteria enzyme is homodimeric [PMID: 11255023, PMID: 20354154].

GO terms

Biological Process

GO:0101030 tRNA-guanine transglycosylation

Molecular Function

GO:0008479 queuine tRNA-ribosyltransferase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.