Fig. 7. mTORC1 controls lysosomal catabolic activity by regulating V-ATPase assembly.

Model for the regulation of lysosomal catabolic activity by mTORC1. a Under amino acid-replete conditions, a large fraction of V-ATPase V₁ domains is stabilized in the cytosol by association with the chaperonin TRiC. Consequently, lysosomes display an elevated pH and low catabolic activity. b Upon amino acid starvation and the ensuing decline in mTORC1 signalling, V₁ domains move to lysosomes and assemble with V_o domains into active proton pumps. The resulting acidification of the lysosomal lumen increases proteolytic activity and initiates degradation of macromolecular contents throughout the organelle population.