Translation in biological cells is the process of protein synthesis directed by a nucleic acid message, mRNA. In the ribosome, each set of three successive nucleotides in the mRNA is matched to a specific amino acid according to the code shown in Table 2. The translation machinery dedicated to interpreting this nucleic acid code operates in a two part process. Amino acids are covalently linked, or ``charged'', to their cognate transfer RNAs (tRNAs) via an aminoacylation reaction catalyzed by a diverse group of multi-domain proteins, the aminoacyl-tRNA synthetases. Charged tRNAs are then shuttled to the ribosome where the tRNA anti-codon is matched to the mRNA codon, and the tRNA is deacylated with the amino acid being added as the next residue of a nascent protein chain [2]. The RNA world hypothesis states that the modern biological world - which relies on DNA and RNA to store genetic information and on proteins to perform catalytic tasks - was pre-dated by and evolved from a form of life that was mostly RNA based, with RNA molecules serving not only to store information, but also to perform required catalytic functions. It is likely that among the first proteins to take over catalytic duties from ribozymes were the aminoacyl-tRNA synthetases (AARSs). These ancient proteins are found in all extant organisms, and their inception clearly pre-dates the root of the universal phylogenetic tree [3,4]. In this tutorial you will use several alignment methods to study and compare various AARSs.
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This codon also specifies the initiator tRNA
.