4E-BP1
Translational repressor; the master effector through which mTORC1 controls protein synthesis. mTORC1 phosphorylates 4E-BP1 to release eIF4E and switch translation ON.
A cap on protein-making that mTORC1 removes. A protein that holds the translation-starter eIF4E hostage - until mTORC1 phosphorylates it, releasing eIF4E and switching protein production on. It's the main effector through which mTORC1 controls how much protein a cell makes.
Only partially rapamycin-sensitive. This goes a long way to explain the rapalog/Torin discrepancy and was a main motivation for ATP-competitive inhibitors.
TL;DR. 4E-BP1 appears in 22 curated studies in Oliver's mTOR Atlas: 2 in people (2 human studies); 4 in animal models; 15 at the molecular level (cells, biochemistry, structure); 1 review. It has 4 interactions in the curated pathway model.
In the pathway model
| Interaction | Mechanism | Evidence | Studies |
|---|---|---|---|
| 4E-BP1 inhibits eIF4E mechanism: competitive-inhibition · this link in full · on the map table | Untagged 4E-BP1 clamps onto eIF4E and blocks it; mTORC1 tags 4E-BP1 to make it let go – releasing a brake, not pressing an accelerator. Holds under: Biochemical and cell-culture evidence (in vitro assays, mammalian and mouse cells, plus one review). It establishes the binding switch itself. It does not measure how much translation changes in a given tissue, in whole animals or in people. plausible in people, not shown directly · settled in the literature | M | MAX2009, THO2012, SCH2003, FIN2002 |
| 4E-BP1 activates Longevity mechanism: functional-consequence · this link in full · on the map table | Keeping 4E-BP switched on extends lifespan in fruit flies on a restricted diet, by protecting their mitochondria. Holds under: Fly only, and only under dietary restriction - the effect was not seen on a full diet. not tested in people · emerging, few independent studies | A | ZID2009 |
| 4E-BP1 context-dependent Mitochondrial biogenesis mechanism: functional-consequence · this link in full · on the map table | The 4E-BP branch helps set how many mitochondrial proteins get built. In mammalian cells it holds them back; in fruit flies on a restricted diet it boosts them, so the direction depends on the organism and the diet. Holds under: Scope: mammalian cells, MOR2013. The sign holds where 4E-BP represses translation of nuclear-encoded mitochondrial mRNAs (TFAM, mitochondrial ribosomal proteins), which is why this branch survives rapamycin better than the S6K arm. It does NOT hold universally across species and nutrient states: in Drosophila under dietary restriction, ZID2009 reports that 4E-BP ENHANCES mitochondrial activity, and that this is how it extends lifespan. Treat the mammalian-cell direction as scoped, not general. not tested in people · emerging, few independent studies | M | MOR2013 conflicting: ZID2009 |
| mTORC1 inhibits 4E-BP1 mechanism: phosphorylation · this link in full · on the map table | mTORC1 tags 4E-BP1 so it lets go of another protein, freeing up protein-building – but the standard drug (rapamycin) only partly blocks this step. Holds under: Cell and in vitro evidence (human and mouse cells, with C. elegans RNAi in one study). Rapamycin blocks this phosphorylation only partly, and individual sites differ in how sensitive they are (KAN2013). Not shown in people by these studies. plausible in people, not shown directly · settled in the literature | M | BUR1998, HARA2002, FEL2009, GIN1999, KAN2013, HAR1998, BRU1997, NOJ2003, SAT2010 |
Evidence at a glance
| Evidence | What it means | Studies |
|---|---|---|
| H | Human study | 2 |
| A | Animal model | 4 |
| M | Molecular — cells, biochemistry, structure | 15 |
| R | Review — secondary literature, not a new result | 1 |
Studies
| Year | Evidence | Study |
|---|---|---|
| 2026 | H | Sexual Dimorphism in Placental mTORC1 Signaling, Amino Acid Transport, and Mitochondrial Respiration at Term. SHIMADA2026 In 46 term placentas, male placentas showed higher mTORC1 signalling (increased S6RP phosphorylation, reduced 4E-BP1), greater System A amino acid transport and higher mitochondrial respiratory capacity than female placentas, and male pregnancies had a higher birth-weight-to-placental-weight ratio. Observational: a cross-sectional association at a single timepoint, with no intervention and no randomisation, so the direction of the relationship between mTORC1 signalling and growth is not established here and residual confounding by maternal and obstetric factors cannot be excluded. |
| 2025 | H | The Bi-steric, mTORC1-Selective Inhibitor, RMC-5552, in Advanced Solid Tumors: A Phase 1 Trial SCH2025 First-in-human, open-label dose-escalation trial (n=57, advanced solid tumors, no comparator arm) of a bi-steric mTORC1-selective inhibitor. Treatment-related hyperglycemia was low (4%) and not dose-limiting, alongside a 64% disease control rate. Because the trial was uncontrolled and made no head-to-head comparison against rapamycin or an ATP-site inhibitor, this is encouraging early clinical evidence consistent with the hypothesis that sparing mTORC2 reduces metabolic toxicity -- it does not establish mTORC2 sparing as the cause. |
| 2026 | A | Lsp2 links mTORC1 to TOP mRNA translation and lifespan in Drosophila WAN2026 Identifies Lsp2, a Drosophila fat-body storage protein, as an amino-acid-induced feedback activator of mTORC1 that specifically boosts translation of TOP-motif mRNAs (mostly ribosomal proteins) via 4E-BP — a rapamycin-resistant arm of mTORC1 output. Genetic loss of Lsp2 reduces TOP mRNA translation and robustly extends lifespan without cost to reproduction, revealing a rapamycin-independent route from mTORC1 activity to organismal longevity. |
| 2023 | A | A bi-steric mTORC1-selective inhibitor overcomes drug resistance in breast cancer MEN2023 RMC-6272, a bi-steric molecule with >25-fold selectivity for mTORC1 over mTORC2, completely suppresses mTORC1 (hitting the rapamycin-resistant substrate 4E-BP1) and overcomes hormone- and CDK4/6-inhibitor resistance in breast cancer cell lines and PDX -- the preclinical basis for the RMC-5552 selective-inhibitor clinical program. |
| 2013 | A | Autism-related deficits via dysregulated eIF4E-dependent translational control GKO2013 Mice lacking 4E-BP2, the main brain brake on eIF4E downstream of mTORC1, showed autism-like behaviours: reduced social approach in the three-chamber test, more self-grooming and marble burying, and more ultrasonic calls as pups. Polysome profiling of hippocampus showed that, of 24 autism-linked mRNAs tested, only the neuroligin 1-4 mRNAs shifted to heavier polysomes in the knockout, with no change in their mRNA levels or in global protein synthesis; eIF4E-overexpressing mice showed the same neuroligin shift. Knockout neurons had larger excitatory than inhibitory synaptic charge transfer, raising the excitation/inhibition ratio. Five days of brain infusion of 4EGI-1, which blocks eIF4E binding to eIF4G, brought cap-bound eIF4E/eIF4G and neuroligin levels back to normal and reversed the social deficit, and knocking down neuroligin 1 (but not neuroligin 2) partly restored social behaviour. Boundary: mouse genetic models (male mice for behaviour); mTOR itself was not manipulated; the link to human autism is by analogy. |
| 2009 | A | 4E-BP extends lifespan upon dietary restriction by enhancing mitochondrial activity in Drosophila ZID2009 Connected the dots between diet, mTOR, and lifespan. 4E-BP, an mTOR target, is upregulated on dietary restriction and here was shown to be REQUIRED for the lifespan boost, working by selectively boosting translation of mitochondrial genes. A rare case pinning a specific mTOR effector to the longevity benefit of eating less. |
| 2015 | M | mTOR regulates the pro-tumorigenic senescence-associated secretory phenotype by promoting IL1A translation LAB2015 Explained HOW rapamycin calms 'inflammaging'. Senescent cells spew inflammatory signals (the SASP) that damage surrounding tissue and even feed tumors. mTOR powers this by translating IL1A, the cytokine at the top of the cascade. Rapamycin selectively shuts it down - and blocked senescent cells from fueling prostate tumor growth in mice. |
| 2013 | M | mTORC1 phosphorylation sites encode their sensitivity to starvation and rapamycin KAN2013 Each mTORC1 phosphorylation site has its own intrinsic 'substrate quality'. Good substrates stay phosphorylated when mTORC1 is partly inhibited by rapamycin or starvation, poor ones drop out first, and changing a few residues around a site shifts its sensitivity in cells. One level of mTORC1 activity can therefore produce different output profiles. |
| 2012 | M | A unifying model for mTORC1-mediated regulation of mRNA translation THO2012 Used ribosome profiling with the complete inhibitor Torin1 to address a long-standing debate: in these cells, mTORC1's translational control runs largely through the 4E-BP family acting on a specific class of mRNAs (TOP motifs). Losing just the 4E-BPs makes translation of TOP mRNAs resistant to mTOR inhibition - naming them the master effectors. |
| 2012 | M | The translational landscape of mTOR signalling steers cancer initiation and metastasis HSI2012 Showed WHY mTOR-driven translation matters for cancer: in prostate cancer, oncogenic mTOR selectively translates a specific set of pro-invasion mRNAs that drive metastasis. An ATP-competitive mTOR inhibitor (INK128) reversed that signature - an early preclinical rationale from mouse models and cell lines, not a clinical result. |
| 2012 | M | Distinct perturbation of the translatome by the antidiabetic drug metformin LAR2012 The authors compared genome-wide changes in mRNA translation caused by metformin with those caused by the mTOR inhibitors rapamycin and PP242 in cancer cells. Metformin changed gene expression at the level of translation to an extent comparable to the classic mTOR inhibitors. Its antiproliferative effect could be explained by selective suppression of translation of mRNAs encoding cell-cycle regulators, acting through the mTORC1 / 4E-BP pathway. The paper provided evidence that metformin's effect on cell growth in vitro goes through selective translational control rather than a general drop in protein synthesis. Boundary: Cultured cancer cells at drug concentrations used in vitro; does not show that metformin at clinical doses acts this way in patients. Drafted from the abstract only. |
| 2010 | M | Single amino-acid changes that confer constitutive activation of mTOR are discovered in human cancer SAT2010 Screened point mutations from cancer genome databases and found two, S2215Y (large intestine adenocarcinoma) and R2505P (renal cell carcinoma), that kept mTOR signalling on even under nutrient starvation. mTORC1 purified from starved cells carrying the mutants still phosphorylated 4E-BP1 in vitro. Mutant cells had more S-phase cells (42.0% vs 28.2% for S2215Y) and resisted the shrinkage caused by amino-acid withdrawal. The mutants stayed sensitive to rapamycin. Boundary: overexpressed mutants in cultured cells; the mutations were found in tumour databases, their driver role in patients was not tested. |
| 2009 | M | An ATP-competitive mammalian target of rapamycin inhibitor reveals rapamycin-resistant functions of mTORC1 THO2009 Dropped a bombshell: rapamycin does NOT fully block mTORC1. Using Torin1 (which jams the active site directly), the authors showed rapamycin leaves important mTORC1 jobs running - notably 4E-BP1 phosphorylation and autophagy suppression. This reframed a decade of rapamycin experiments and launched the search for complete inhibitors. |
| 2009 | M | Ku-0063794 is a specific inhibitor of the mammalian target of rapamycin (mTOR) GAR2009 Ku-0063794 is a specific ATP-competitive mTOR inhibitor blocking mTORC1 and mTORC2. |
| 2009 | R | Translational control of long-lasting synaptic plasticity and memory COS2009 This review gathers evidence that long-lasting synaptic plasticity and long-term memory depend on new protein synthesis, and that the step where mRNA translation starts is a main control point. It covers two arms: the mTORC1 arm (4E-BP2, eIF4E, S6K) that controls cap-dependent translation, and the eIF2alpha arm (GCN2, PKR, ATF4) that controls general translation and specific mRNAs. It also discusses how faulty translational control is linked to disorders such as fragile X syndrome and tuberous sclerosis. It is a summary of work by many labs and gives the field a shared framework rather than new data. Boundary: narrative review; the cited evidence is mainly from rodent slices, rodent behaviour and invertebrate models, not from people. |
| 2003 | M | The mammalian target of rapamycin (mTOR) partner, raptor, binds the mTOR substrates p70 S6 kinase and 4E-BP1 through their TOR signaling (TOS) motif NOJ2003 Raptor binds mTOR substrates via their TOS motifs, acting as the substrate-presenting scaffold of mTORC1. |
| 2002 | M | Mammalian cell size is controlled by mTOR and its downstream targets S6K1 and 4EBP1/eIF4E FIN2002 mTOR controls mammalian cell size through its downstream translational targets S6K1 and 4E-BP1/eIF4E. |
| 2002 | M | Tuberous sclerosis complex-1 and -2 gene products function together to inhibit mammalian target of rapamycin (mTOR)-mediated downstream signaling TEE2002 The authors coexpressed hamartin (TSC1) and tuberin (TSC2) in cultured cells and followed two main outputs of mTOR. Together, the two proteins reduced phosphorylation of 4E-BP1, so more 4E-BP1 stayed bound to the translation factor eIF4E; a TSC2 mutant found in TSC patients was defective at this. Hamartin plus tuberin also lowered S6K1 activity, but did not affect S6K1 mutants that resist rapamycin, which points to mTOR as the step being blocked. In nutrient-deprived cells, hamartin and tuberin prevented amino acids from switching S6K1 back on. The authors concluded that the TSC1-TSC2 complex acts as an inhibitor of mTOR signalling and suggested that TSC tumours may come from too much mTOR activity. Boundary: overexpression in cultured mammalian cells; the link to tumours in TSC patients is a proposal, not tested in patient tissue here. |
| 2002 | M | A rapamycin-sensitive signaling pathway contributes to long-term synaptic plasticity in the hippocampus TAN2002 The authors showed that mTOR, 4E-BP1, 4E-BP2 and eIF4E are present in rat hippocampus and sit in dendrites, close to synapses, where their staining overlapped with the postsynaptic protein PSD-95. Blocking mTOR with rapamycin in hippocampal slices reduced late-phase long-term potentiation (LTP) after high-frequency stimulation, while early-phase LTP was unaffected. Rapamycin also blocked the synaptic potentiation induced by the growth factor BDNF. This was one of the early papers to tie a rapamycin-sensitive pathway to the protein-synthesis-dependent phase of synaptic plasticity and to suggest it controls local translation at synapses. Boundary: rodent brain slices and cultured neurons; mTOR targets were localised but their phosphorylation during LTP was not reported in the abstract; no behaviour or memory test. |
| 1999 | M | Regulation of 4E-BP1 phosphorylation: a novel two-step mechanism GIN1999 4E-BP1 is phosphorylated by an ordered, priming two-step mechanism that controls its release of eIF4E. |
| 1998 | M | Amino acid sufficiency and mTOR regulate p70 S6 kinase and eIF-4E BP1 through a common effector mechanism HAR1998 Amino acid sufficiency signals through mTOR to p70 S6K and 4E-BP1 via a common effector, first linking nutrients to mTOR. |
| 1997 | M | Phosphorylation of the translational repressor PHAS-I by the mammalian target of rapamycin BRU1997 mTOR directly phosphorylates 4E-BP1 (PHAS-I), releasing eIF4E and establishing mTOR's role in translational control. |
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