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. Author manuscript; available in PMC: 2014 Jul 4.
Published in final edited form as: Cell Cycle. 2010 May 15;9(10):1869–1870. doi: 10.4161/cc.9.10.11679

Figure 1.

Figure 1

Role of the late endosome in regulating mTOR-Rheb interactions. In upper left, a normal cell undergoes early to late endosomal conversion through the action of Rab5 and the HOPS complex. Amino acids can drive the localization of mTOR from cytosol to late endosomes, where mTOR has been suggested to interact with Rheb. In lower left, overexpression of exogenous Rheb leads to Rheb-mTOR interactions even in the absence of amino acids. This activates mTORC1 in an amino acid- and localization-independent manner. In the upper right panel, hybrid early/late endosomes have been formed by Rab5 CA overexpression or hVps39 knockdown. mTOR can still translocate to the hybrid endosomes under amino acid stimulated conditions, but this compartment cannot support mTORC1 signaling, most likely due to reduced Rheb-mTOR interactions. In the bottom right panel, overexpression of exogenous Rheb bypasses the requirement for late endosomes and drives Rheb-mTOR interactions driven by mass action.