SZT2 (Seizure Threshold 2), originally known as C1orf84, is a large protein (approximately 378 kDa) located at chromosome 1p34.2. As a core subunit of the KICSTOR complex, it localizes to the lysosomal surface and negatively regulates the mTORC1 signaling pathway by recruiting the GATOR1 complex. Loss of SZT2 function leads to constitutive activation of mTORC1, resulting in aberrant cell proliferation, overproliferation of neural stem cells, and impaired neuronal differentiation. This protein plays a critical role in nervous system development and cell growth regulation, making it an important target for research on neurodevelopmental disorders and epilepsy.