As a component of the GATOR1 complex functions as an inhibitor of the amino acid-sensing branch of the TORC1 pathway. The GATOR1 complex strongly increases GTP hydrolysis by RRAGA and RRAGB within RRAGC-containing heterodimers, thereby deactivating RRAGs, releasing mTORC1 from lysosomal surface and inhibiting mTORC1 signaling. The GATOR1 complex is negatively regulated by GATOR2 the other GATOR subcomplex in this amino acid-sensing branch of the TORC1 pathway. Within the GATOR complex, component of the GATOR1 subcomplex, made of DEPDC5, NPRL2 and NPRL3. GATOR1 mediates the strong interaction of the GATOR complex with RRAGA/RRAGC and RRAGB/RRAGC heterodimers. Interacts (via DEP domain) with KLHL22; the interaction depends on amino acid availability. Localization to lysosomes is amino acid-independent. Expressed at low levels in all brain regions. Expressed throughout brain development, including in midgestation embryonic head (11.5 dpc), neonatal brain and whole adult brain. Present in neurons and absent in non-neuronal cells, including astrocytes (at protein level). The DEP domain mediates the interaction with KLHL22. Ubiquitinated. Amino acid-induced 'Lys-48'-linked polyubiquitination of DEPDC5 by the BCR(KLHL22) ubiquitin ligase complex leads to DEPDC5 proteasomal degradation and inhibition of the GATOR1 complex. Ubiquitination may occur at multiple lysines. Belongs to the IML1 family. Extended N-terminus.