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. Author manuscript; available in PMC: 2014 Dec 1.
Published in final edited form as: Curr Opin Cell Biol. 2013 Jul 24;25(6):10.1016/j.ceb.2013.07.002. doi: 10.1016/j.ceb.2013.07.002

Figure 1.

Figure 1

Activation of mTORC1 occurs at the lysosomal surface. Amino acid levels are sensed through an inside-out mechanism using the lysosomal V-ATPase. The sensing mechanism also includes the Ragulator complex, which acts as a guanine nucleotide exchange factor (GEF) for the Rag family of GTP binding proteins. The activity of mTOR is negatively regulated by AMPK that senses AMP and ADP levels during energy depleted conditions, or is activated by a variety of other energy sensors including LKB1.