As part of the KICSTOR complex functions in the amino acid-sensing branch of the TORC1 signaling pathway. Recruits, in an amino acid-independent manner, the GATOR1 complex to the lysosomal membranes and allows its interaction with GATOR2 and the RAG GTPases. Functions upstream of the RAG GTPases and is required to negatively regulate mTORC1 signaling in absence of amino acids. In absence of the KICSTOR complex mTORC1 is constitutively localized to the lysosome and activated. The KICSTOR complex is also probably involved in the regulation of mTORC1 by glucose (PubMed:28199306, PubMed:28199315). May play a role in the cellular response to oxidative stress (By similarity). Part of the KICSTOR complex composed of KPTN, ITFG2, KICS2 and SZT2. SZT2 probably serves as a link between the other three proteins in the KICSTOR complex and mediates the direct interaction with the GATOR1 complex. Localization to lysosomes is amino acid-independent. Expressed in the brain, predominantly in the parietal and frontal cortex, as well as in dorsal root ganglia. Expressed in peripheral white blood cells. The disease is caused by variants affecting the gene represented in this entry. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus. Probable cloning artifact. Probable cloning artifact. Contaminating sequence. Sequence of unknown origin in the N-terminal part.