RRAGA (Ras-related GTP-binding protein A) is a key regulator of mTORC1 nutrient sensing on the lysosomal membrane. RRAGA functions as a GTPase that senses amino acid availability, particularly leucine, and controls mTORC1 recruitment to lysosomes for activation 1. As a component of the Rag-Ragulator complex, RRAGA serves as the central organizer of mTORC1 pathway architecture, with its nucleotide state controlling lysosomal association of regulatory complexes including GATOR1, GATOR2, and KICSTOR 2. The Rag-Ragulator complex presents substrates like TFEB to mTORC1 for phosphorylation in a RagC GDP-dependent manner 3. RRAGA participates in stress responses, where membrane Atg8ylation recruits RRAGA-containing complexes to damaged lysosomes to inactivate mTORC1 4. RRAGA mutations cause autosomal dominant cataracts through disrupted mTORC1 signaling, increased lysosomal RRAGA relocation, elevated mTORC1 phosphorylation, and compromised autophagy in lens epithelial cells 5. RRAGA-dependent mTORC1 inhibition promotes autophagy and virus replication during glucosamine treatment 6, while STING1-mediated MTORC1 activation involves RRAGA and RRAGC in hepatic lipid metabolism regulation 7. RRAGA overexpression has been associated with depression onset 1.