Figure 1.

Sensors and transducers in metabolic signaling. (A) Metabolic signaling is triggered by a metabolite sensor protein that directly binds to a metabolite. The sensor then engages transducers in a signaling pathway that eventually activate responses through an effector protein. (B) In mammalian models, amino acids are sensed directly by diverse sensor proteins that activate the mechanistic target of rapamycin (mTOR), a central regulatory hub that transduces diverse upstream signals to coordinate metabolism. mTOR then phosphorylates additional transducers and effectors, such as LARP1 and S6K, to promote protein synthesis and repress autophagy.