A. Protein components of the amino acid sensing branch of the mTORC1 pathway.
B. GATOR1 binds to the Rag GTPase heterodimer via two modes: an inhibitory mode and a GAP mode. A point mutation on the critical strip, DEPDC5(Y775A), blocks binding in the inhibitory mode.
C. Scheme for GATOR1-stimulated GTP hydrolysis assay (GAP assay)..
D–G. Stimulated GTP hydrolysis by wild-type Rag GTPases in the presence or absence of Ragulator, with wild-type GATOR1 (D), GATOR1[DEPDC5(Y775A)] (E), GATOR1[DEPDC5(P)] (F), and NPRL2-NPRL3 (G) as stimulant..
H. Summary of kinetic parameters from panels D–G. Gray numbers in parentheses denote the SEMs of the reported values calculated from three independent experiments.