Abstract
Aminoacyl-tRNAs are generally formed by direct attachment of an amino acid to tRNAs by aminoacyl-tRNA synthetases, but glutaminyl-tRNA (Q-tRNA) is an exception to this rule. Glutaminyl-tRNAGln (Q-tRNAQ) is formed by this direct pathway in the eukaryotic cytosol and in a small subset of bacteria, but is formed by an indirect transamidation pathway in most bacteria and archaea. To date it is almost impossible to predict what pathway generates organellar Q-tRNAQ in a given eukaryote. All eukaryotic genomes sequenced so far display a single glutaminyl-tRNA synthetase (QRS) gene which is at least responsible for the cytosolic QRS activity, as well as a gene coding for a mitochondrial ortholog of the essential GatB subunit of the tRNA-dependent amidotransferase (AdT). Indeed, QRS activity was found in protozoan mitochondria while AdT activity was characterized in plant organelles. The pathway for Q-tRNAQ synthesis in yeast and mammals mitochondria is still questionable.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
