MIOS functions as a critical component of the GATOR2 complex, which serves as an activator of the amino acid-sensing branch of the mTORC1 signaling pathway 12. The GATOR2 complex, containing five subunits including MIOS, adopts a large cage-like architecture with MIOS forming part of an octagonal scaffold alongside WDR24 and WDR59 subunits 2. Mechanistically, GATOR2 indirectly activates mTORC1 by inhibiting the GATOR1 subcomplex through ubiquitination mechanisms, with GATOR2 functioning as an E3 ubiquitin-protein ligase 1. In amino acid-rich conditions, GATOR2 mediates ubiquitination of NPRL2, a core GATOR1 component, leading to GATOR1 inactivation and subsequent mTORC1 activation 1. Within the GATOR2 complex, MIOS specifically prevents autoubiquitination of WDR24, the catalytic subunit, ensuring complex stability 2. The complex also mediates interactions with amino acid sensors SESN2 and CASTOR1 through its WD40 β-propeller domains 2. Disease relevance includes potential involvement in cancer, as GATOR components can be mutated in human malignancies where mTORC1 becomes hyperactive and insensitive to amino acid starvation 1. GATOR2 is also required for brain myelination, suggesting broader developmental significance 2.