mTOR and its Downstream Targets

The mammalian target of rapamycin (mTOR) is a protein kinase that plays key roles in regulating cellular functions. mTOR forms two distinct multiprotein complexes, mTOR complexes 1 and 2 (mTORC1/2), which phosphorylate different substrates. Rapamycin inhibits many functions of mTORC1. Its use has revealed that mTORC1 regulates protein synthesis, ribosome production, autophagy, gene transcription, and cell growth and division. mTORC1's best-known substrates are proteins involved in protein synthesis. mTORC2 phosphorylates protein kinases such as Akt. Defects in mTOR signaling or its control are involved in various diseases, including cancers, and mTOR signaling is thus a potentially valuable therapeutic target.