The Target of Rapamycin: Structure and Functions

The target of rapamycin (TOR, also called the mechanistic or mammalian target of rapamycin, mTOR) is an atypical protein kinase that is highly conserved in eukaryotes (Sarbassov et al. 2005; Wullschleger et al. 2006; Jacinto & Lorberg 2008). It modulates cell growth, metabolism, and cell survival in response to diverse extracellular and intracellular signals, such as growth factors, energy levels, and nutrient status (Reiling & Sabatini 2006; Wullschleger et al. 2006; Jacinto 2008). Inhibition of mTOR activity using rapamycin and more recently via mTOR active site inhibitors and disruption of mTOR complexes, has revealed important insights on how mTOR functions under physiological and pathological conditions (Sarbassov et al. 2005; Proud 2011; Zoncu et al. 2011).