Queuosine-tRNA galactosyltransferase (QTGAL)

Queuosine-tRNA galactosyltransferase (QTGAL), encoded by the B3GNTL1 gene, is an enzyme belonging to the glycosyltransferase family GT2[1]. Its function is to catalyze the transfer of galactose from UDP-galactose to queuosine-modified tRNA^Tyr^, resulting in the formation of galactosyl-queuosine (galQ) at the wobble position of the tRNA. This post-transcriptional modification of tRNA regulates translation by attenuating the increased decoding speed induced by queuosine, acting as a negative regulator for optimal translation rates, and preventing stop codon readthrough during protein synthesis. Loss of galQ modification leads to accelerated translation of specific codons, increased protein misfolding, and aggregation, thereby compromising cellular proteostasis. QT GAL activity requires UDP-galactose as a substrate, and the enzyme relies on queuine, a micronutrient derived from gut microbiota and diet. Aberrations in queuosine or galQ metabolism have been linked to disorders suchs as neurodegenerative disease (via proteostasis defects), cancer (through altered translation and cell growth), and cellular stress responses (UPR activation)[1][2][3]. QTGAL does not currently have therapeutic drugs targeting it directly, but its activity is relevant for understanding translational control and proteostasis in mammals.

Other names

B3GNTL1BGnT-like protein 1Beta-1,3-Gn-T8Beta1,3-N-acetylglucosaminyltransferase-like protein 1Beta3Gn-T-like protein 1Beta-1,3-N-acetylglucosaminyltransferase 8BGnT-8B3GNT8QTGALbeta3GnTL1UDP-GlcNAc:betaGal beta-1,3-N-acetylglucosaminyltransferase-like protein 1UDP-GlcNAc:betaGal beta-1,3-N-acetylglucosaminyltransferase 8beta-1,3-Gn-T8beta3Gn-T8