As a component of the GATOR subcomplex GATOR2, functions within the amino acid-sensing branch of the TORC1 signaling pathway. Indirectly activates mTORC1 and the TORC1 signaling pathway through the inhibition of the GATOR1 subcomplex (PubMed:23723238). It is negatively regulated by the upstream amino acid sensors SESN2 and CASTOR1 (PubMed:25457612, PubMed:27487210). Within the GATOR complex, component of the GATOR2 subcomplex, made of MIOS, SEC13, SEH1L, WDR24 and WDR59. The GATOR complex strongly interacts with RRAGA/RRAGC and RRAGB/RRAGC heterodimers. The GATOR2 complex interacts with CASTOR2 and CASTOR1; the interaction is negatively regulated by arginine (PubMed:26972053). The GATOR2 complex interacts with the sestrins SESN1, SESN2 and SESN3; the interaction is negatively regulated by amino acids (PubMed:25263562, PubMed:25457612, PubMed:26586190). Belongs to the WD repeat mio family.