EcAsnRS_like_N: N-terminal, anticodon recognition domain of the type found in Escherichia coli asparaginyl-tRNA synthetase (AsnRS) and, in Arabidopsis thaliana and Saccharomyces cerevisiae mitochondrial (mt) AsnRS. This domain is a beta-barrel domain (OB fold) involved in binding the tRNA anticodon stem-loop. The enzymes in this group are homodimeric class2b aminoacyl-tRNA synthetases (aaRSs). aaRSs catalyze the specific attachment of amino acids (AAs) to their cognate tRNAs during protein biosynthesis. This 2-step reaction involves i) the activation of the AA by ATP in the presence of magnesium ions, followed by ii) the transfer of the activated AA to the terminal ribose of tRNA. In the case of the class2b aaRSs, the activated AA is attached to the 3'OH of the terminal ribose. Eukaryotes contain 2 sets of aaRSs, both of which are encoded by the nuclear genome. One set concerns with cytoplasmic protein synthesis, whereas the other exclusively with mitochondrial protein synthesis. S. cerevisiae mtAsnRS can charge E.coli tRNA with asparagines. Mutations in the gene for S. cerevisiae mtAsnRS has been found to induce a "petite" phenotype typical for a mutation in a nuclear gene that results in a non-functioning mitochondrial protein synthesis system.
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