Stefanie S. Schalm
Cell biologist who, in John Blenis's lab, showed that the TOS motif lets raptor grab 4E-BP1 so mTORC1 can phosphorylate it, and who later moved into cancer drug discovery in the biotech industry
Kymera Therapeutics, Watertown (2025 paper) · Blueprint Medicines, Cambridge, Massachusetts (2022 paper) · Department of Molecular and Cellular Biology, Harvard University, Tom Maniatis lab (2010) · Department of Cell Biology, Harvard Medical School, John Blenis lab (2000–2004)
Stefanie Schalm is first author of the Atlas study SCH2003 from John Blenis's lab at Harvard Medical School. It explains how mTORC1, the growth-control complex, recognises one of its main targets. 4E-BP1 is a brake on protein synthesis: while unphosphorylated it holds on to eIF4E, the factor that binds the cap at the start of a messenger RNA. Once mTORC1 adds several phosphate groups, 4E-BP1 lets go and translation can begin.
The paper showed that a short stretch at the end of 4E-BP1, the TOR signalling (TOS) motif, is what binds raptor, the partner protein that hands substrates to mTOR. Without a working TOS motif, raptor could not bind 4E-BP1 and the multiple phosphorylation steps failed, so 4E-BP1 kept blocking translation. It established the TOS motif as a docking signal on 4E-BP1 for mTORC1. The experiments were done in cultured cells.
With Blenis, Schalm also co-wrote a 2004 review on how the PI3-kinase and TOR pathways join to control cell growth. By 2010 PubMed lists Schalm in Tom Maniatis's group in Harvard's Department of Molecular and Cellular Biology, studying how the receptor kinase Ret phosphorylates protocadherins, adhesion proteins of nerve cells. Later papers list Blueprint Medicines (2022), on a kinase inhibitor approach for fibrolamellar liver cancer, and Kymera Therapeutics (2025), on a drug that degrades the p53 inhibitor MDM2.
Milestones in the Atlas
A selection, not a full bibliography: only papers that meet the Atlas inclusion criteria.
| Year | Evidence | Study |
|---|---|---|
| 2003 | M | TOS motif-mediated raptor binding regulates 4E-BP1 multisite phosphorylation and function SCH2003 First author: showed in cultured cells that the TOS motif of 4E-BP1 mediates raptor binding and is needed for its multisite phosphorylation by mTORC1. |
Co-authors in the Atlas 3
People with a profile here who share at least one study with Stefanie S. Schalm.
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- David M. Sabatini Identified mTOR (as RAFT1) in 1994. His lab then mapped much of the machinery around it: raptor and rictor at the core of mTORC1 and mTORC2, the Rag–Ragulator system that docks mTORC1 on the lysosome, and the sensors that detect leucine, arginine and SAM
- Diane C. Fingar Studies how mTORC1 and mTORC2 are regulated, especially through site-specific phosphorylation
- John Blenis Showed early on that rapamycin blocks S6 kinase, then worked out how mTORC1 drives cell growth through its two main translation targets, S6K1 and 4E-BP1. His lab also found, in parallel with the Sabatini lab, that mTORC1 phosphorylates Grb10, a feedback brake on insulin signalling
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