MTOR

mTOR (mechanistic target of rapamycin) is a kinase that integrates growth factors, nutrients, energy state, and stress into a single decision about whether the cell should build biomass.

Function

mTOR functions in two multiprotein complexes. mTORC1 (with RAPTOR) responds to amino acids, growth factors (through the PI3K–AKT route), and high energy charge; it phosphorylates S6K and 4E-BP1, which drives ribosome biogenesis and cap-dependent translation — the cell’s protein-synthesis program. mTORC2 (with RICTOR) phosphorylates AKT on Ser473 and controls cytoskeletal organization. Rapamycin binds FKBP12 and inhibits mTORC1 allosterically, the mechanism behind the drug’s immunosuppressive and lifespan-extending effects.

In cancer

The pathway is hyperactivated in most human cancers, through PTEN