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Updated: May 14, 2026

Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids
Published on: January 26, 2012
Citric acid cycle and the origin of MARS
Sandeepa M Eswarappa1, Paul L Fox
1Department of Cellular & Molecular Medicine, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue/NC10, Cleveland, OH 44195, USA.
Abstract:
The vertebrate multiaminoacyl tRNA synthetase complex (MARS) is an assemblage of nine aminoacyl tRNA synthetases (ARSs) and three non-synthetase scaffold proteins, aminoacyl tRNA synthetase complex-interacting multifunctional protein (AIMP)1, AIMP2, and AIMP3. The evolutionary origin of the MARS is unclear, as is the significance of the inclusion of only nine of 20 tRNA synthetases. Eight of the nine amino acids corresponding to ARSs of the MARS are derived from two citric acid cycle intermediates, α-ketoglutatrate and oxaloacetate. We propose that the metabolic link with the citric acid cycle, the appearance of scaffolding proteins AIMP2 and AIMP3, and the subsequent disappearance of the glyoxylate cycle, together facilitated the origin of the MARS in a common ancestor of metazoans and choanoflagellates.
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