Liron Bar-Peled
Defined the GAP and GEF switches that control the Rag GTPases
PhD, Sabatini lab, Whitehead Institute/MIT · Rullo Family Endowed Chair in Cancer Research, Massachusetts General Hospital & Harvard Medical School
Bar-Peled Lab, MGH & Harvard ↗ Bluesky@liron1bar-peled.bsky.social ↗
As a graduate student in David Sabatini's lab, Liron Bar-Peled showed that the Ragulator complex acts as a GEF (guanine nucleotide exchange factor) that switches the Rag GTPases on, and then identified GATOR1 as the GAP (GTPase-activating protein) complex that switches them back off — together defining the molecular on/off switch that gates amino-acid signalling to mTORC1.
Bar-Peled now leads his own lab at Massachusetts General Hospital and Harvard Medical School, where his research has broadened to how cancer cells manage metabolic and oxidative stress, including the discovery that SLC38A9 senses lysosomal arginine to activate mTORC1.
The timeline below follows Bar-Peled's contributions gathered in this Atlas.
Milestones in the Atlas
| Year | Evidence | Study |
|---|---|---|
| 2010 | M | Ragulator-Rag complex targets mTORC1 to the lysosomal surface and is necessary for its activation by amino acids SAN2010 Established WHERE mTORC1 gets switched on: the lysosome surface. Identified Ragulator as the lysosomal dock that recruits the Rag GTPases and drags mTORC1 to the membrane where its activator Rheb lives. Amino acids work by controlling this translocation. |
| 2011 | M | mTORC1 senses lysosomal amino acids through an inside-out mechanism that requires the vacuolar H(+)-ATPase ZON2011 Showed amino acid sensing starts INSIDE the lysosome: amino acids accumulate in the lumen and the v-ATPase relays that signal outward ('inside-out') to Ragulator-Rag. A surprising twist on where the cell measures its nutrient status. |
| 2012 | M | Ragulator is a GEF for the rag GTPases that signal amino acid levels to mTORC1 BAR2012 Shows Ragulator is a GEF for the Rag GTPases, switching them on to signal amino-acid sufficiency to mTORC1. |
| 2013 | M | A Tumor suppressor complex with GAP activity for the Rag GTPases that signal amino acid sufficiency to mTORC1 BAR2013 Identifies GATOR1 as a tumor-suppressor GAP complex that switches the Rag GTPases off in the absence of amino acids. |
On the programme
Meetings in the Atlas calendar where Liron Bar-Peled is listed among the speakers or organisers.
- past Prague Metabolism and Signaling Symposium 2026 ↗ 24–27 Jun 2026 · Prague, Czech Republic · Tier 1
- past Keystone: Mitochondria Signaling in Physiology and Disease 2026 ↗ 9–12 Feb 2026 · Keystone, Colorado, USA · Tier 3