Figure 3. mTORC1 signaling and regulation.

mTORC1, which regulates various cellular events such as cell growth, autophagy, and mRNA translation, is activated by insulin-stimulated and Akt-mediated phosphorylation and inhibition of TSC1/2, a negative regulator of mTOR. Inhibition of TSC1/2 leads to the activation of small G protein Rheb and thus enhanced mTORC1 signaling. mTORC1-mediated phosphorylation of Grb10 at Ser^501/503 switches the binding preference of Grb10 from the insulin receptor to Raptor, leading to the dissociation of Raptor from mTOR and thus down-regulation of mTORC1 signaling.