Yeast FLCN-FNIP orthologues function to modulate TORC1 activity

Péli-Gulli et al., (2015) report that amino acid stimulation of TORC1 activity in yeast is dependent on the function of Lst4 and Lst7 – orthologues of FLCN and FNIP1 – as the GAP complex for the Rag GTPase Gtr2. In amino-acid starved cells the Lst4-Lst7 complex is clustered at the vacuolar membrane where it can, upon amino acid stimulation, act on Gtr2 enabling TORC1 activation. This functional orthologue of the mammalian FLCN-FNIP complex thereby provides a link between amino acid stimulation, such as increased glutamine levels, and TORC1 activation in yeast cells. This model system could be useful in understanding increased glutamine dependency in mTORC-1 associated tumours.

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