Fig. 4 |. Logic of mTORC1 regulation and function.
a, mTORC1 senses the nutrients required to make the macromolecular products whose synthesis mTORC1 promotes and thereby coordinately controls macromolecular synthesis and autophagic turnover. Under nutrient-replete conditions, mTORC1 suppresses autophagy while driving parallel synthesis of nutrient-derived macromolecules to support cell growth. b, Depletion of any individual nutrient inhibits mTORC1 and dampens the synthesis of all macromolecules downstream of mTORC1. The resulting inhibition of mTORC1 also enables induction of autophagy, which recycles macromolecules into their nutrient components. c, The logic of mTORC1 regulation as an AND gate requiring both sufficient nutrients and a signal from exogenous growth factors for full activation. Nutrients are generally sufficient to yield low basal activation of mTORC1, sufficient to suppress autophagy, for instance, and required for mTORC1 activation by growth factors.