Tyrosyl-tRNA synthetase, cytoplasmic, also known as Tyrosine-tRNA ligase, is an enzyme that in humans is encoded by the YARS gene. Aminoacyl-tRNA synthetases catalyze the aminoacylation of transfer RNA (tRNA) by their cognate amino acid. Tyrosyl tRNA synthetase from Bacillus stearothermophilus is a dimeric enzyme, consisting of two identical sub-units (MW 2 x kDa). It catalyses the formation. Tyrosyl-tRNA Synthetase (TyrRS) is an enzyme found in Methanocaldococcus Jannaschii that catalyzes the attachment of tyrosine to its cognate tRNA to form.


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YARS - Wikipedia

Pf-YARS is expressed in all asexual parasite stages rings, trophozoites and schizonts and is exported to the host erythrocyte cytosol, from where it is released into blood plasma on iRBC rupture. It genome encodes four aminoacyl-tRNA synthetases: The crystal structure of the mimivirus tyrosyl-tRNA synthetase in complex with tyrosinol has been solved at 2.

The mimiviral YARS exhibits the typical fold and active-site organization of archaeal-type YARSs, with an N-terminal Rossmann-fold catalytic domain, an anticodon binding domain, tyrosyl trna synthetase no extra C-terminal domain. It presents a unique dimeric conformation tyrosyl trna synthetase significant differences in its anticodon binding site, when compared with the YARSs from other organisms.

Thus, the pseudo-dimer contains only one functional active site contributed by the N-terminal half and only one functional anticodon recognition site contributed by the C-terminal half. Its recognition tyrosyl trna synthetase both subunits of the tyrosyl-tRNA synthetase dimer.

It tyrosyl trna synthetase takes part in protein synthesis by getting inserted into an elongating polypeptide chain 2. In the forward tyrosylation reaction, tRNA acts as a magnesium complex 8.

In the reverse reaction, though, tyrosyl-tRNA is not bound to any magnesium ions 8.


The magnesium ion also takes part in post-transfer steps of the tyrosyl-tRNA synthetase reaction by functioning as a catalyst 8. Conformational changes are a key part in TyrRS function as well.

Tyrosine—tRNA ligase

By undergoing multiple tyrosyl trna synthetase changes, the transition state during the first step of the tyrosylation reaction is stabilized 1.

This tells us that an induced-fit model is being applied in the first step of the reaction 1.

Dali is a program that seeks proteins with similarities in tertiary structure to a protein query. The server does this by implementing a sum-of-pairs method that measures intramolecular distances.

Resultant protein matches are assigned a Z-score tyrosyl trna synthetase quantify structural similarity.


Typically, Z-scores of 2 or higher identify proteins with significant similarities in folding. In this reaction, tyrosine is first activated by reaction tyrosyl trna synthetase ATP to form the enzyme bound intermediate, tyrosine adenylate, with the liberation of pyrophosphate.

Although the enzyme is dimeric, only 1 molecule of tyrosine is bound per dimer, resulting in only 1 molecule of product tyrosyl trna synthetase dimer.

Catalysis of Tyrosyl tRNA formation The progress of this reaction can be readily studied using filter binding assays with radiolabelled substrates.

TRNA Synthetase

A key feature of this system that has made it particularly amenable to study is the stability tyrosyl trna synthetase the tyrosyl adenylate intermediate formed in step 1. If the enzyme is incubated with tyrosine and ATP in the presence of inorganic pyrophosphatase, which hydrolyses the pyrophosphate formed in step 1, then the reverse reaction is blocked and the enzyme-tyrosyl adenylate complex is formed stoichiometrically.

This has two important consequences: It allows the concentration of active sites to be measured precisely using the radioactive assay.

tyrosyl trna synthetase

This is particularly important when comparing data from mutant enzymes since changes in Vmax must be caused by changes in Km and kcat and not for the trivial reason that there is a change tyrosyl trna synthetase the tyrosyl trna synthetase of enzyme which remains functional.

It is possible to crystallise the intermediate complex and determine its structure by X-ray crystallography. Splicing events retain noncatalytic domains while ablating the catalytic domain to create catalytic nulls with diverse functions.

Each synthetase is converted into several new signaling proteins with biologic activities 'orthogonal' to that of the catalytic parent. The recombinant aminoacyl tRNA synthetase variants had specific biologic activities across a spectrum of cell-based assays: