tRNALys

tRNALys is a transfer RNA that carries the amino acid lysine to the ribosome during protein synthesis. It is one of the many tRNA species that interpret the genetic code by pairing its anticodon with lysine codons on messenger RNA. In most organisms, lysine is encoded by two codons, AAA and AAG, and tRNALys exists as two main isoacceptors that recognize them. The anticodons of these tRNAs are typically written as 5'-UUU-3' to read AAA and 5'-CUU-3' to read AAG, reflecting the antiparallel base pairing between codon and anticodon.

The canonical structure of tRNALys, like most tRNAs, is a cloverleaf with an acceptor stem ending in CCA at the 3' terminus, where lysine is covalently attached by the enzyme lysyl-tRNA synthetase (LysRS). The aminoacyl-tRNA is delivered to the ribosome by elongation factor Tu (EF-Tu in bacteria) bound to GTP, and participates in correct decoding at the A site.

Genes encoding tRNALys are present in multiple copies in many genomes. In bacteria there are two LysRS isoacceptors that charge the different tRNALys species; in eukaryotes and archaea, transcription is carried out by RNA polymerase III and tRNALys genes are dispersed within the nuclear genome, with mitochondrial and plastid genomes encoding their own tRNALys in certain lineages. tRNALys often carries post-transcriptional modifications, especially around the anticodon and the 3' end, which influence decoding fidelity and stability.