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. It is negatively regulated by the upstream amino acid sensors SESN2 and CASTOR1. 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. The GATOR2 complex interacts with the sestrins SESN1, SESN2 and SESN3; the interaction is negatively regulated by amino acids. Belongs to the WD repeat mio family.