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| Title | Structure of the lysosomal KICSTOR-GATOR1-SAMTOR nutrient-sensing supercomplex. |
|---|---|
| Journal, issue, pages | Cell, Year 2026 |
| Publish date | Jan 8, 2026 |
Authors | Christopher J Lupton / Charles Bayly-Jones / Shuqi Dong / Terrance Lam / Wentong Luo / Gareth D Jones / Chantel Mastos / Nicholas J Frescher / San S Lim / Alastair C Keen / Luke E Formosa / Hari Venugopal / Yong-Gang Chang / Michelle L Halls / Andrew M Ellisdon / ![]() |
| PubMed Abstract | The guanosine triphosphate (GTP)-bound state of the heterodimeric Rag GTPases functions as a molecular switch regulating mechanistic target of rapamycin complex 1 (mTORC1) activation at the lysosome ...The guanosine triphosphate (GTP)-bound state of the heterodimeric Rag GTPases functions as a molecular switch regulating mechanistic target of rapamycin complex 1 (mTORC1) activation at the lysosome downstream of amino acid fluctuations. Under low amino acid conditions, GTPase-activating protein (GAP) activity toward Rags 1 (GATOR1) promotes RagA GTP hydrolysis, preventing mTORC1 activation. KICSTOR recruits and regulates GATOR1 at the lysosome by undefined mechanisms. Here, we resolve the KICSTOR-GATOR1 structure, revealing a striking ∼60-nm crescent-shaped assembly. GATOR1 anchors to KICSTOR via an extensive interface, and mutations that disrupt this interaction impair mTORC1 regulation. The S-adenosylmethionine sensor SAMTOR binds KICSTOR in a manner incompatible with metabolite binding, providing structural insight into methionine sensing via SAMTOR-KICSTOR association. We discover that KICSTOR and GATOR1 form a dimeric supercomplex. This assembly restricts GATOR1 to an orientation that favors the low-affinity active GAP mode of Rag GTPase engagement while sterically restricting access to the high-affinity inhibitory mode, consistent with a model of an active lysosomal GATOR1 docking complex. |
External links | Cell / PubMed:41512879 |
| Methods | EM (single particle) |
| Resolution | 3.34 - 5.0 Å |
| Structure data | EMDB-70140, PDB-9o5d: EMDB-70141, PDB-9o5e: |
| Source |
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Keywords | CELL CYCLE / Lysosome / GATOR1 / KICSTOR / cell growth / amino acid sensing / mTOR / KPTN / ITFG2 / C12orf66 / SZT2 / NPRL2 / NPRL3 / DEPDC5 |
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