RRAGC (RagC) and RRAGD (RagD) are guanyl nucleotide-binding proteins that hydrolyze GTP (Tsun et al. 2013, Shen et al. 2017). The GDP-bound form of RRAGC,D is the active form that recruits mTORC1 to the lysosomal membrane (Tsun et al. 2013). RRAGC,D forms a heterodimer with RRAGA,B that has two stable conformations: RRAGA,B:GTP:RRAGC,D:GDP (active) or RRAGA,B:GDP:RRAGC,D:GTP (inactive) (Shen et al. 2017). Folliculin (FLCN) complexed with FNIP1 or FNIP2 interacts with RRAGA (Petit et al. 2013) and acts as a GTPase activator (GAP) for RRAGC:GTP and RRAGD:GTP (Tsun et al. 2013). FLCN is located at the lysosomal membrane during amino acid starvation and in the cytosol during amino acid stimulation (Tsun et al. 2013).