LRS (Leucyl-tRNA synthetase) has been shown to work like a switch that regulates the synthesis of amino acid by POSTECH researchers.
The joint research team of Professor Sung Ho Ryu (Life), Prof. Sunghoon Kim and Prof. Jung Min Han of SNU Integration Core Center have found that LRS plays a critical role in amino acid-induced mammalian target of rapamycin (mTOR) activation.
Leucine is an essential amino acid that stimulates protein synthesis, helps turn on the body’s switch to build muscle, and spares muscle when dieting. Previously, LRS has been known as the enzyme which transports leucine to ribosome, where protein chains are synthesized, but the amino acid sensor which directly couples intracellular amino acid-mediated signaling to mTORC1 was unknown. 
The research team demonstrated that LRS works as a carrier of leucine to ribosome. It is also a key mediator for amino acid signaling to mTORC1, which regulates protein translation, cell size, and authop- hagy, by sensing intracellular leucine concentration and initiating molecular interaction leading to mTORC1 activation.
The research team found that LRS combines with mTOR. Since rapamycin has immunosuppressive and anti-proliferative properties, it is expected as the breakth- rough of cancer treatment.
The research team expects that the research results can deepen the underst- anding of the LRS mechanism of cancer, diabetes, and aging. They predict that LRS will be the target of the development of new pharmaceuticals.