Rap1-GTPases control mTORC1 activity by coordinating lysosome organization with amino acid availability

mTORC1 regulates cellular growth from the lysosome, but how changes in the organisation of the lysosomal system affect mTORC1 signalling is poorly understood. Here the authors show that amino acid-dependent Rap1-mediated changes in lysosomal abundance determine overall signalling output of mTORC1.