Forms part of a macromolecular complex that catalyzes the attachment of specific amino acids to cognate tRNAs during protein synthesis. Modulates the secretion of AIMP1 and may be involved in generation of the inflammatory cytokine EMAP2 from AIMP1.
The aminoacyl t-RNA synthetase interacting multifunctional protein (AIMP1) is the precursor of the multifunctional inflammatory cytokine endothelial monocyte-activating polypeptide II (EMAP II). We previously demonstrated that AIMP1 secretion by pituitary adenomas is inversely correlated with tumor diameter and with RARS expression, suggesting that a high amount of RARS associated with AIMP1 might prevent the secretion of the latter cytokine. In this study, we investigated the role of RARS in modulating the secretion of AIMP1 in HeLa and MCF7 cell lines and investigated the possible role of the multicatalytic protease in the cleavage of AIMP1 to generate EMAP II. Our data show that RARS over-expression impairs AIMP1 secretion by both HeLa and MCF7 cells. Moreover, proteasome inhibition impairs AIMP1 cleavage to produce EMAP II. These data indicate that RARS over-expression associates with a reduced AIMP1 secretion and that the multicatalytic protease is involved in the generation of the mature cytokine, EMAP II.
Interacting selectively and non-covalently with any protein or protein complex (a complex of two or more proteins that may include other nonprotein molecules).
Evidence
1:
Inferred from Physical InteractionIntAct
Human cytosolic leucyl-tRNA synthetase is one component of a macromolecular aminoacyl-tRNA synthetase complex. This is unlike prokaryotic and lower eukaryotic LeuRSs that exist as free soluble enzymes. There is little known about it, since the purified enzyme has been unavailable. Herein, human cytosolic leucyl-tRNA synthetase was heterologously expressed in a baculovirus system and purified to homogeneity. The molecular mass (135 kDa) of the enzyme is close to the theoretical value derived from its cDNA. The kinetic constants of the enzyme for ATP, leucine, and tRNA(Leu) in the ATP-PP(i) exchange and tRNA leucylation reactions were determined, and the results showed that it is quite active as a free enzyme. Human cytosolic leucyl-tRNA synthetase expressed in human 293 T cells localizes predominantly to the cytosol. Additionally, it is found to have a long C-terminal extension that is absent from bacterial and yeast LeuRSs. A C-terminal 89-amino acid truncated human cytosolic leucyl-tRNA synthetase was constructed and purified, and the catalytic activities, thermal stability, and subcellular location were found to be almost identical to native enzyme. In vivo and in vitro experiments, however, show that the C-terminal extension of human cytosolic leucyl-tRNA synthetase is indispensable for its interaction with the N-terminal of human cytosolic arginyl-tRNA synthetase in the macromolecular complex. Our results also indicate that the two molecules interact with each other only through their appended domains.
The process of coupling arginine to arginyl-tRNA, catalyzed by arginyl-tRNA synthetase. In tRNA aminoacylation, the amino acid is first activated by linkage to AMP and then transferred to either the 2'- or the 3'-hydroxyl group of the 3'-adenosine residue of the tRNA.
IEAOrtholog Compara
Enzymatic activity
This protein acts as an enzyme. It is known to catalyze the following reaction
Protein involved in the biosynthesis of proteins from mRNA molecules. This process, called translation, is carried out by ribosomes, where activated amino acids are added to the nascent polypeptide chain.
Enzyme that activates an amino acid for translation by forming an aminoacyladenylate intermediate and then links this activated amino acid to the corresponding tRNA molecule (amino acid-tRNA, aminoacyl- tRNA). In general, a specific aminoacyl-tRNA synthase is available for each amino acid.
Enzyme that catalyzes the joining of two molecules coupled with the breakdown of a pyrophosphate bond in ATP or a similar triphosphate. Sometimes the terms "synthase", "synthetase" or "carboxylase" are also used for this class of enzymes.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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