Novel regulatory interactions and activities of mammalian tRNA synthetases.

Aminoacyl-tRNA synthetases (ARSs) catalyze the attachment of specific amino acids to their cognate tRNAs, thereby ensuring the faithful translation of genetic code. In addition to their enzymatic function, these enzymes have been discovered to regulate various cellular functions such as tRNA export, ribosomal RNA synthesis, apoptosis, inflammation and angiogenesis in mammalian. The insights into the noncanonical activities of these enzymes have been obtained from their unique cellular localization, interacting partners, isoform generation and expression control. Mammalian ARSs also form a macromolecular protein complex with a few auxiliary factors. Although the physiological significance of this complex is poorly understood, it also supports the potential of mammalian ARSs as sophisticated multifunctional proteins for regulating various cellular procedures. In this review, the novel regulatory activities of mammalian ARSs will be discussed in different biological processes.