Mechanistic target of rapamycin kinase (mTOR) within mechanistic target of rapamycin complex 1 (mTORC1) (mTORC1)

The mechanistic target of rapamycin complex 1 (mTORC1) is a highly conserved serine/threonine protein kinase complex that functions as a master regulator of cellular metabolism and growth [1, 10]. It integrates a variety of environmental and intracellular signals, including nutrient availability (particularly amino acids), energy levels (ATP), oxygen status, and growth factor signaling [1, 7]. The complex is composed of the mTOR catalytic subunit along with several regulatory proteins, including Raptor, mLST8, PRAS40, and Deptor [10, 13]. When activated, mTORC1 promotes anabolic processes such as protein synthesis, lipid biogenesis, and ribosome production, while simultaneously inhibiting catabolic processes like autophagy [4, 9]. Dysregulation of the mTORC1 pathway is implicated in a wide range of human pathologies, most notably in cancer, where hyperactivation drives uncontrolled cell proliferation and survival [2, 16]. It also plays a critical role in metabolic diseases like type 2 diabetes and obesity, as well as genetic disorders such as Tuberous Sclerosis Complex (TSC) [5, 11]. Therapeutic targeting of mTORC1 began with the discovery of rapamycin (sirolimus) and its analogs (rapalogs), which inhibit the complex allosterically by binding to FKBP12 [6, 14]. More recently, second-generation ATP-competitive inhibitors have been developed to provide more comprehensive inhibition of the mTOR kinase activity, aiming to overcome the limitations and feedback loops associated with rapalogs [8, 17].

Other names

mTOR Complex 1Mammalian target of rapamycin complex 1FRAP1 complexRAptor-mTOR complex

Allosteric inhibition (rapalogs bind FKBP12 and then the FRB domain of mTOR); ATP-competitive inhibition (second-generation inhibitors target the catalytic site)