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. Author manuscript; available in PMC: 2010 Feb 1.
Published in final edited form as: Biochem Soc Trans. 2009 Feb;37(Pt 1):248–252. doi: 10.1042/BST0370248

Figure 1. Growth regulation from the inside.

Figure 1

Rag GTPases are required to activate mTOR in response to amino acids [28, 29] and for mTOR to be shuttled to late (Rab7-positive) endosomes, which also contain the mTOR activator Rheb. The PAT amino acid transporters [35, 36] are TOR regulators [37] that can potentially operate in endosomal and lysosomal compartments, as well as at the cell surface. In this review, we suggest that the Rags might play a role in shuttling the PATs to late endosomes, from which they can help to recruit TOR, presumably leading to the activation of S6 kinase. The PATs would provide a means of utilising late endosomal versus extracellular amino acids, which may be particularly important under nutrient-deprived conditions.