{"gene":"RHEB","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":2003,"finding":"TSC2 is a GTPase-activating protein (GAP) directly toward Rheb; TSC2 stimulates Rheb GTP hydrolysis, reducing active Rheb-GTP levels, and thereby inhibiting mTOR-dependent phosphorylation of S6K and 4EBP1. Rheb acts downstream of TSC1/TSC2 and upstream of mTOR.","method":"In vitro GAP activity assays, co-immunoprecipitation, dominant-negative and constitutively active mutant expression, genetic epistasis in mammalian cells","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — biochemical GAP assay plus genetic epistasis, independently replicated by multiple labs in the same year","pmids":["12869586","12842888","12766776","12766775"],"is_preprint":false},{"year":2003,"finding":"Rheb is an essential regulator of S6 kinase (S6K) activity downstream of Tsc1/Tsc2 and upstream of TOR in Drosophila; loss-of-function Rheb mutations arrest larval growth and prevent G1-S progression, and overexpression promotes cell and tissue growth in a rapamycin-sensitive manner.","method":"Drosophila genetic screen, loss-of-function mutations, overexpression, rapamycin sensitivity assay","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with multiple alleles, replicated in two independent Drosophila studies","pmids":["12766776","12766775","12893813"],"is_preprint":false},{"year":2004,"finding":"TSC2 GAP activity toward Rheb requires a catalytic 'asparagine thumb' (Asn residues in TSC2) rather than the arginine finger found in Ras-GAPs; Arg15 of Rheb (equivalent to Gly12 in Ras) is important for Rheb to serve as a TSC2 GAP substrate. Farnesylation and membrane localization of Rheb are not essential for Rheb to stimulate S6K phosphorylation.","method":"Site-directed mutagenesis, in vitro GAP activity assay, cell-based S6K phosphorylation assay","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of GAP activity with mutagenesis, single lab with multiple orthogonal methods","pmids":["15340059"],"is_preprint":false},{"year":2005,"finding":"Rheb binds directly to the mTOR catalytic domain and to LST8 within mTOR complex 1 (TOR complex 1), independently of its ability to bind TSC2. Rheb-GTP binding enables activation of the TOR kinase; mTOR polypeptides bound to Rheb(Gln64Leu) (near-90% GTP-charged) exhibit substantially higher kinase activity, while nucleotide-deficient Rheb mutants bind mTOR but trap it in an inactive state.","method":"Co-immunoprecipitation (in vivo and in vitro), in vitro kinase assay, switch-I domain mutagenesis, nucleotide-charging analysis","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — reciprocal co-IP, in vitro kinase assay with multiple Rheb mutants, direct biochemical reconstitution","pmids":["15854902"],"is_preprint":false},{"year":2005,"finding":"Amino acid withdrawal reversibly inhibits binding of Rheb to endogenous and recombinant mTOR without altering Rheb GTP-charging. The inhibitory effect is exerted through an action on mTOR at a site largely distinct from the Rheb-binding region; deletion of the C-terminal lobe of the mTOR catalytic domain abolishes the inhibitory effect of amino acid withdrawal on Rheb binding.","method":"Co-immunoprecipitation, mTOR deletion mutants, GTP-charging assays, amino acid withdrawal/re-addition experiments","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — multiple orthogonal methods in one study, direct biochemical measurement of Rheb-mTOR interaction under defined conditions","pmids":["15878852"],"is_preprint":false},{"year":1994,"finding":"Rheb is a novel Ras-family small GTPase that binds and hydrolyzes GTP and contains a C-terminal CAAX box predicted to signal farnesylation for membrane targeting. It is rapidly and transiently induced in hippocampal neurons by seizures and NMDA-dependent synaptic activity.","method":"Differential cloning, bacterial fusion protein GTP-binding and GTPase activity assay, Northern blot, sequence analysis","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — direct in vitro GTPase assay, single lab, original characterization paper","pmids":["8206940"],"is_preprint":false},{"year":1997,"finding":"Rheb is farnesylated in vitro and in vivo and is sensitive to farnesyltransferase inhibition. Unlike Ras, Rheb does not transform NIH 3T3 cells but instead antagonizes oncogenic Ras transformation and signaling, similar to KRev-1/Rap1A.","method":"In vitro and in vivo farnesylation assays, NIH 3T3 transformation assay, oncogenic Ras co-expression","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1–2 / Weak — direct farnesylation assay and transformation assay, single lab","pmids":["9099708"],"is_preprint":false},{"year":1997,"finding":"Rheb interacts with Raf-1 kinase; unlike H-Ras, the Rheb-Raf-1 interaction is potentiated by growth factors combined with cAMP-elevating agents. Protein kinase A-dependent phosphorylation of Ser43 in Raf-1 reciprocally potentiates Raf-1 binding to Rheb and decreases its interaction with H-Ras. A single amino acid in the G2 effector domain is critical for the differential binding properties of Rheb versus Ras.","method":"Co-immunoprecipitation, mutagenesis, cAMP stimulation, PKA phosphorylation assays","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Weak — co-IP with mutagenesis, single lab","pmids":["9001246"],"is_preprint":false},{"year":2002,"finding":"Rheb is maintained in a high GTP-bound (activated) state in mammalian cells, much more so than Ras or Rap1, and its activation state is unaffected by changes in growth conditions. Rheb binds B-Raf kinase and inhibits B-Raf kinase activity and B-Raf-dependent Elk-1 transcriptional activation.","method":"GTP/GDP loading assays in three mammalian cell lines, co-immunoprecipitation of endogenous Rheb with B-Raf, in vitro kinase assay, Elk-1 reporter assay","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple cell lines, co-IP plus kinase assay, single lab","pmids":["12214276"],"is_preprint":false},{"year":2003,"finding":"TSC2 binds Rheb-GTP in vitro and reduces Rheb GTP levels in vivo; overexpression of Rheb but not Rap1 promotes S6 kinase activation in a rapamycin-dependent manner. Rheb-mediated S6 phosphorylation is blocked by a farnesyl transferase inhibitor.","method":"In vitro pulldown (Rheb-GTP binding), in vivo GTP-loading assay, S6K phosphorylation assay, FTI treatment","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — biochemical binding assay combined with in vivo GTP loading and functional assay, replicated across labs","pmids":["12842888"],"is_preprint":false},{"year":2004,"finding":"Constitutive activation of the Rheb/mTOR/S6K cassette (by TSC1/TSC2 deletion or ectopic Rheb expression) is sufficient to induce insulin resistance by downregulating IRS1 and IRS2, rendering Akt refractory to activation by IRS-dependent growth factor pathways.","method":"Genetic deletion of TSC1/TSC2 in mouse embryonic fibroblasts, ectopic Rheb overexpression, Western blot for IRS1/IRS2 protein levels and Akt phosphorylation","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic deletion plus ectopic expression, multiple orthogonal readouts, single lab","pmids":["15380067"],"is_preprint":false},{"year":2004,"finding":"Rheb inhibits wild-type B-Raf kinase activity and this function is independent of mTOR/rapamycin (mTOR-independent). The interaction of endogenous Rheb with B-Raf is enhanced by serum and Ras overexpression. A farnesylation-defective Rheb mutant can still co-immunoprecipitate with and inhibit B-Raf, indicating that farnesylation is not required for B-Raf inhibition by Rheb. B-Raf inhibition and S6K activation are separable activities of Rheb.","method":"Co-immunoprecipitation, in vitro B-Raf kinase assay, rapamycin treatment, farnesylation-defective Rheb mutant","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (co-IP, kinase assay, mutagenesis), single lab","pmids":["15150271"],"is_preprint":false},{"year":2005,"finding":"Rheb localizes to endomembranes (endoplasmic reticulum, Golgi) rather than the plasma membrane, dependent on C-terminal CAAX farnesylation but not palmitoylation. Rce1 and Icmt post-prenylation processing steps are required for proper Rheb endomembrane localization; without the polybasic region or palmitoylation sites, Rheb diffusely localizes when Rce1 or Icmt are absent.","method":"Confocal microscopy with fluorescent protein fusions, Rce1 and Icmt knockout fibroblasts, farnesyltransferase and geranylgeranyltransferase inhibitors, CAAX cysteine mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — direct imaging in genetically defined knockout cells combined with pharmacological and mutagenesis controls, single lab with multiple orthogonal approaches","pmids":["16046393"],"is_preprint":false},{"year":2005,"finding":"Rheb farnesylation (via the C-terminal CAAX motif) is completely blocked by the FTI SCH66336 (lonafarnib) and Rheb is not alternatively geranylgeranylated. Rheb and Rheb2 C-terminal peptides are substrates for farnesyltransferase but not geranylgeranyltransferase-1 in vitro. FTI-mediated inhibition of mTOR/S6 signaling is reversed by a Rheb mutant engineered for geranylgeranylation, establishing Rheb as the critical FTI target for mTOR pathway inhibition.","method":"In vitro prenylation assay with purified enzymes, metabolic labeling in cell culture, S6 phosphorylation assay, Rheb CSVL geranylgeranylatable mutant rescue","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — direct in vitro prenylation assay combined with cell-based rescue experiments with specific mutant, single lab","pmids":["16006564"],"is_preprint":false},{"year":2006,"finding":"Rheb inhibits both B-Raf and C-Raf kinase activities and inhibits B-Raf/C-Raf heterodimerization; these effects are rapamycin-insensitive (mTOR-independent). Rheb activation is associated with decreased B-Raf (Ser-446) and C-Raf (Ser-338) phosphorylation and inhibits the association of B-Raf with H-Ras.","method":"In vitro kinase assay, co-immunoprecipitation of B-Raf/C-Raf heterodimers, rapamycin treatment","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple biochemical assays, single lab, consistent with prior findings","pmids":["16803888"],"is_preprint":false},{"year":2006,"finding":"Drosophila Rheb (dRheb) has an inhibitory effect on dTORC2 activity in Drosophila S2 cells; this appears to be mediated by a feedback mechanism involving dTORC1 and dS6K rather than direct Rheb-TORC2 interaction. Mammalian Rheb does not activate TORC2 in HEK293 cells. TSC1/TSC2 have opposite effects on TORC1 and TORC2.","method":"S2 cell RNAi, Akt and S6K phosphorylation as TORC2/TORC1 functional readouts, Drosophila genetics","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic and biochemical approaches in two cell systems, single lab","pmids":["16627617"],"is_preprint":false},{"year":2007,"finding":"Rheb activates mTOR by antagonizing FKBP38, an endogenous inhibitor of mTOR structurally related to FKBP12; Rheb interacts directly with FKBP38 in a GTP-dependent manner and prevents FKBP38 association with mTOR.","method":"Co-immunoprecipitation, in vitro binding assay, RNAi knockdown, mTOR kinase assay","journal":"Science (New York, N.Y.)","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — co-IP and functional assay, single lab; note that subsequent work (PMID:19222999) failed to detect Rheb-FKBP38 interaction in vitro, creating contradictory evidence","pmids":["17991864"],"is_preprint":false},{"year":2009,"finding":"The Rheb-FKBP38 interaction proposed in Science 2007 was not detected in three independent in vitro assay systems; cell biological experiments show FKBP38 plays only a very minor role, if any, in mTORC1 activation. FKBP38 is therefore not the long-sought Rheb effector linking Rheb to mTORC1 activation.","method":"Three independent in vitro binding assays, cell biological experiments","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — multiple orthogonal in vitro assays explicitly refuting prior claim; recorded as negative finding","pmids":["19222999"],"is_preprint":false},{"year":2009,"finding":"Rheb specifically activates mTORC1 but not mTORC2 in a GTP-dependent manner in vitro; the activation requires the effector domain of Rheb and a raptor-containing mTORC1 complex. Rheb increases binding of the substrate 4E-BP1 to mTORC1. Other GTPases (KRas, RalA/B, Cdc42) do not activate mTORC1. Rheb does not induce mTOR autophosphorylation. FKBP38-depleted mTORC1 preparations are still activated by Rheb.","method":"In vitro mTORC1 kinase assay using immunoprecipitated mTORC1 from nutrient-starved cells, recombinant Rheb addition, effector domain mutants, substrate binding assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct in vitro reconstitution with multiple controls and mutants, single lab","pmids":["19299511"],"is_preprint":false},{"year":2008,"finding":"Rheb directly binds and activates PLD1 (but not PLD2) in a GTP-dependent manner in vitro, establishing PLD1 as a bona fide effector of Rheb. PLD1 is required (by RNAi) for Rheb activation of the mTOR pathway; TSC2 overexpression suppresses PLD1 activation, and TSC2 deletion elevates basal PLD activity.","method":"In vitro binding and PLD activity assay with recombinant proteins, RNAi knockdown, PLD activity assay, PI3K/AMPK pharmacological inhibitors","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct in vitro protein–protein interaction and enzyme activation assay, corroborated by RNAi in cells, single lab","pmids":["18550814"],"is_preprint":false},{"year":2009,"finding":"Rheb inhibits aggresome formation and sensitizes cells to death upon misfolded protein accumulation by disrupting the interaction between dynein and misfolded protein cargos, thereby blocking dynein-dependent retrograde transport. This function is independent of mTOR complex 1.","method":"Genetic TSC1/TSC2 knockout cells, Rheb overexpression/knockdown, co-immunoprecipitation of dynein with misfolded protein cargos, rapamycin treatment to distinguish mTOR-dependent from mTOR-independent effects","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic and biochemical approaches, rapamycin used to demonstrate mTOR independence, single lab","pmids":["19458266"],"is_preprint":false},{"year":2009,"finding":"Rheb localizes primarily to endoplasmic reticulum and Golgi apparatus (Rheb1 and Rheb2). Post-prenylation processing by Rce1 and Icmt is required for proper Rheb localization but dispensable for Rheb-induced activation of S6K; farnesylthiosalicylic acid (FTS) blocks S6K activation induced by constitutively active mTOR downstream of Rheb, suggesting FTS inhibits mTOR downstream of Rheb.","method":"Immunofluorescence microscopy, Rce1 and Icmt knockout cells, S6K phosphorylation assay, FTS treatment","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization in knockout cells combined with functional S6K assay, single lab","pmids":["19838215"],"is_preprint":false},{"year":2011,"finding":"PRAK (p38-regulated/activated kinase) directly phosphorylates Rheb at Ser130, which impairs the nucleotide-binding ability of Rheb and inhibits Rheb-mediated mTORC1 activation. This operates downstream of a p38β-PRAK cascade activated by energy starvation, independently of AMPK-mediated TSC2 and Raptor phosphorylation.","method":"In vitro kinase assay (PRAK phosphorylating Rheb), site-directed mutagenesis of Ser130, nucleotide binding assay, mTORC1 activity assay, PRAK/p38β depletion experiments","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct in vitro kinase assay with mutagenesis, nucleotide binding assay, and genetic epistasis, single lab with multiple orthogonal methods","pmids":["21336308"],"is_preprint":false},{"year":2008,"finding":"Rheb overexpression induces multiple axon formation in hippocampal neurons via mTOR; Rheb suppression by RNAi blocks axon specification. mTOR acts through 4E-BP1 translation control; downstream of Rheb-mTOR, Rap1B levels are maintained by counteracting Smurf2-mediated degradation.","method":"Neuronal overexpression/RNAi in dissociated hippocampal neurons, morphological readout (axon number), rapamycin inhibition, 4E-BP1 mutant expression, Smurf2 RNAi rescue","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — epistasis via multiple RNAi and dominant constructs, direct morphological readout, single lab","pmids":["18842593"],"is_preprint":false},{"year":2008,"finding":"ATF6α transcription factor induces Rheb expression, which activates mTOR signaling independently of Akt, promoting survival of quiescent/dormant tumor cells. Knockdown of ATF6α or Rheb reverts dormant tumor cell resistance to rapamycin.","method":"shRNA knockdown of ATF6α and Rheb, rapamycin treatment, in vivo dormancy model, mTOR activity assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockdown with in vivo validation and functional pathway epistasis, single lab","pmids":["18650380"],"is_preprint":false},{"year":2010,"finding":"Tsc2–Rheb signaling controls EphA receptor-dependent axon guidance; EphA receptor activation by ephrin-A ligands decreases ERK1/2-mediated inhibition of Tsc2, thereby inactivating the mTOR pathway. Tsc2 deficiency with hyperactive Rheb constitutively activates mTOR and inhibits ephrin-induced growth cone collapse.","method":"Tsc2 haploinsufficient mice (retinogeniculate projection analysis), ERK1/2 activity assay in neurons, growth cone collapse assay, mTOR activity assays","journal":"Nature neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic mouse model combined with cellular biochemical assays, multiple readouts, single lab","pmids":["20062052"],"is_preprint":false},{"year":2017,"finding":"Cryo-EM structure of RHEB-mTORC1 at 3.4 Å shows RHEB binds to mTOR distally from the kinase active site and causes a global conformational change that allosterically realigns active-site residues to accelerate catalysis. Cancer-associated hyperactivating mutations map to elements that maintain the inactive state and biochemically mimic RHEB relieving auto-inhibition.","method":"Cryo-EM structure determination (3.0 Å mTORC1; 3.4 Å RHEB-mTORC1), crystal structures of RAPTOR-TOS and mTOR FRB-substrate complexes, in vitro kinase assays, biochemical characterization of cancer mutations","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — near-atomic resolution cryo-EM structure with biochemical validation, defines allosteric activation mechanism","pmids":["29236692"],"is_preprint":false},{"year":2018,"finding":"Ubiquitination of Rheb by the lysosome-anchored E3 ligase RNF152 promotes Rheb binding to the TSC complex and keeps Rheb inactive. EGF activates AKT-dependent phosphorylation of USP4, causing deubiquitination of Rheb and its release from the TSC complex, enabling mTORC1 activation.","method":"Co-immunoprecipitation, ubiquitination assays, RNF152 and USP4 knockdown/overexpression, AKT inhibition, mTORC1 activity assays","journal":"Cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP with ubiquitination assay and genetic perturbations, single lab","pmids":["30514904"],"is_preprint":false},{"year":2015,"finding":"MCRS1 is required for amino acid-dependent mTORC1 activation by maintaining Rheb at lysosome surfaces; MCRS1 suppression promotes Rheb/TSC2 interaction, renders Rheb inactive, and relocalizes Rheb from lysosomes to recycling endocytic vesicles.","method":"siRNA knockdown, inducible Cre/lox MEFs, co-immunoprecipitation (Rheb-TSC2, Rheb-MCRS1), immunofluorescence localization of Rheb","journal":"Developmental cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus localization in two genetic systems, single lab","pmids":["25816988"],"is_preprint":false},{"year":2015,"finding":"Rheb inhibits protein synthesis by enhancing phosphorylation of eIF2α through activation of the ER kinase PERK, in a manner independent of mTORC1.","method":"Rheb overexpression and knockdown, eIF2α phosphorylation assays, PERK inhibition/knockdown, protein synthesis assays","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — functional assay with genetic perturbations, mTORC1 independence shown, single lab","pmids":["25660019"],"is_preprint":false},{"year":2013,"finding":"GTP-bound Rheb interacts with BACE1 (β-secretase) and promotes its degradation through proteasomal and lysosomal pathways, independently of mTOR signaling. Rheb overexpression depletes BACE1 protein and reduces Aβ generation, while Rheb knockdown promotes BACE1 accumulation.","method":"Co-immunoprecipitation (GTP-Rheb with BACE1), proteasome and lysosome inhibitor experiments, Rheb overexpression/RNAi, Aβ measurement","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP combined with functional degradation assays and mTOR-independent demonstration, single lab","pmids":["24368770"],"is_preprint":false},{"year":2016,"finding":"Arginine suppresses lysosomal localization of the TSC complex and its interaction with Rheb, thereby relieving allosteric inhibition of Rheb by TSC and enabling maximal mTORC1 activation by growth factors. This mechanism does not involve regulation of mTORC1 lysosomal localization.","method":"Lysosomal fractionation, co-immunoprecipitation of TSC2 with Rheb under arginine-replete vs. -depleted conditions, mTORC1 activity assays in multiple cell types including hESC-derived lineages","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Moderate — lysosomal fractionation plus co-IP in multiple cell types, single lab with multiple orthogonal methods","pmids":["26742086"],"is_preprint":false},{"year":2021,"finding":"Structural analysis at near-atomic resolution reveals the TSC complex has an arch-shaped 2:2:1 (TSC1:TSC2:TBC1D7) stoichiometry. Structural and biochemical analysis of the TSC2 GAP domain–Rheb interface confirms that the TSC2 asparagine thumb (N1643) stabilizes the γ-phosphate of GTP to accelerate Rheb GTP hydrolysis.","method":"Cryo-EM structure of human TSC complex, biochemical GAP activity assays, mutagenesis of catalytic residues","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — near-atomic resolution cryo-EM combined with biochemical mutagenesis, single study with multiple orthogonal methods","pmids":["33436626"],"is_preprint":false},{"year":2021,"finding":"Rheb is dynamically trafficked to the mitochondrial matrix through its interaction with Tom20 in response to neuronal activity and lactate. Mitochondria-localized Rheb activates pyruvate dehydrogenase (PDH) by physically associating with PDH phosphatase (PDP), enhancing PDP activity and its association with the catalytic E1α-subunit of PDH to reduce PDH phosphorylation and increase acetyl-CoA and ATP production. This function is independent of mTORC1.","method":"SC-specific Rheb knockout mice and gain-of-function models, mitochondrial fractionation, co-immunoprecipitation (Rheb-Tom20, Rheb-PDP), PDH activity assay, acetyl-CoA and ATP measurement, rapamycin comparison","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — direct biochemical interaction assay plus enzymatic activity assay with genetic models, mTORC1-independent function validated by rapamycin, single lab with multiple orthogonal approaches","pmids":["33725483"],"is_preprint":false},{"year":2021,"finding":"SC-specific Rheb knockout suppresses pyruvate dehydrogenase (PDH) activity independently of mTORC1 and shifts pyruvate metabolism toward lactate production in Schwann cells, causing age-dependent peripheral axon degeneration.","method":"Schwann cell-specific Rheb knockout mice, PDH activity assay, lactate measurement, peripheral nerve function tests","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — conditional knockout with biochemical and physiological phenotypic readouts, mTORC1 independence noted, single lab","pmids":["34619097"],"is_preprint":false},{"year":2019,"finding":"ATF6 transcription factor directly transcriptionally induces RHEB expression (confirmed by chromatin immunoprecipitation) in cardiac myocytes, which activates mTORC1 to promote compensatory cardiac hypertrophy. ATF6 cardiac-specific knockout blunts hypertrophy and is rescued by ectopic RHEB.","method":"Chromatin immunoprecipitation (ATF6 on RHEB promoter), cardiac-specific ATF6 knockout mice (TAC and exercise models), AAV9-RHEB rescue, mTORC1 activity assays","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — ChIP identifies RHEB as direct ATF6 target, confirmed by conditional KO and rescue in vivo, single lab with multiple orthogonal methods","pmids":["30582446"],"is_preprint":false},{"year":2018,"finding":"A small molecule (NR1) binds Rheb in the switch II domain and selectively blocks mTORC1 signaling (inhibits S6K1 phosphorylation) without inhibiting AKT or ERK. Unlike rapamycin, NR1 does not cause prolonged mTORC2 inhibition. Rheb switch II domain point mutations that impair mTORC1 activation are mimicked by NR1 binding.","method":"Small molecule binding assay (NR1 binding to Rheb switch II), S6K1/AKT/ERK phosphorylation assays in cells, in vivo mouse kidney and muscle mTORC1 assay, comparison with rapamycin","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct biochemical binding to switch II domain with functional specificity assays in vitro and in vivo, single lab","pmids":["29416044"],"is_preprint":false},{"year":2017,"finding":"Rheb inhibits beiging of white adipose tissue through an mTORC1-independent mechanism involving stabilization of PDE4D5, which degrades cAMP and reduces PKA activity and UCP1 expression. Adipose-specific Rheb knockout increases cAMP, PKA activity, and UCP1; partial, but not complete, rescue by rapamycin confirms the mTORC1-independent component.","method":"Adipose-specific Rheb knockout mice, cAMP measurement, PKA activity assay, PDE4D5 protein stability assay, rapamycin treatment comparison, primary adipocyte overexpression","journal":"Diabetes","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional knockout with multiple biochemical readouts, mTORC1-independent mechanism supported by rapamycin partial rescue, single lab","pmids":["28242620"],"is_preprint":false},{"year":2011,"finding":"Rheb knockout mice die around midgestation, most likely due to impaired cardiovascular development; Rheb-null embryonic fibroblasts show decreased TORC1 activity, reduced cell size, and impaired proliferation. Rheb heterozygosity extends the lifespan of Tsc1-null embryos, establishing genetic interaction between Tsc1 and Rheb in vivo.","method":"Rheb knockout mouse generation, embryonic phenotype analysis, embryonic fibroblast TORC1 activity and cell size assays, Tsc1/Rheb double-mutant epistasis","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic knockout mouse with biochemical and genetic epistasis validation, single lab","pmids":["21321084"],"is_preprint":false},{"year":2019,"finding":"In Treg cells, Rheb1 and Rheb2 (Rheb GTPases) are central regulators of amino acid-dependent mTORC1 activation; mice with Rheb1/Rheb2-deficient Treg cells develop fatal autoimmune disease with reduced effector Treg accumulation. Rheb1/Rheb2 enforce the eTreg cell suppressive gene signature, whereas Rag GTPases regulate mitochondrial and lysosomal fitness.","method":"Conditional Treg-specific Rheb1/Rheb2 double-knockout mice, mTORC1 activity assays, immune phenotyping, gene expression profiling","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Moderate — conditional double-knockout mouse model with mTORC1 activity assays and defined autoimmune phenotype, single lab","pmids":["31668641"],"is_preprint":false},{"year":2010,"finding":"NMR structure of Rheb-GDP shows the canonical Ras GTPase fold with GDP-dependent dynamics in the switch I and II regions. NMR revealed Ras effector-like binding of activated Rheb to the c-Raf Ras-binding domain (RBD) but with ~1000-fold lower affinity than Ras/RBD, suggesting lack of functional interaction with c-Raf.","method":"NMR structure determination of Rheb-GDP, NMR binding assay (Rheb to c-Raf RBD), affinity measurement","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — NMR structure with binding measurement, single study, negative result for functional Raf interaction recorded","pmids":["20685651"],"is_preprint":false},{"year":2011,"finding":"Rheb and raptor negatively regulate skeletal myogenic differentiation through suppression of IRS1; knockdown of Rheb enhances myogenic differentiation with increased Akt activation and elevated IRS1 protein levels and reduced IRS1 Ser307 phosphorylation. IRS1 knockdown eliminates the enhancement elicited by Rheb knockdown, placing IRS1 downstream of the Rheb-mTOR/raptor inhibitory pathway in myogenesis.","method":"C2C12 myoblast siRNA knockdown and overexpression, myogenic differentiation assays, IRS1/Akt phosphorylation Western blots, epistasis by IRS1 co-knockdown","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis in cell line with multiple perturbations, single lab","pmids":["21852229"],"is_preprint":false},{"year":2019,"finding":"Brain somatic doublet mutation RHEB p.Y35L increases Rheb GTPλS-binding activity, elevates mTOR/S6 phosphorylation in cells, and when expressed via in utero electroporation in mice causes cytomegalic neurons, dysregulated neuron migration, abnormal EEG, and seizures recapitulating focal cortical dysplasia type II; rapamycin rescues the EEG and seizure phenotype.","method":"Whole exome sequencing, GTPλS binding assay, in utero electroporation in mice, S6 phosphorylation assay, EEG recording, rapamycin treatment","journal":"Experimental & molecular medicine","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — direct biochemical characterization of gain-of-function mutation combined with in vivo mouse model with pharmacological rescue, single lab","pmids":["31337748"],"is_preprint":false}],"current_model":"RHEB is a farnesylated Ras-family small GTPase that is maintained in a predominantly GTP-bound state and functions as the direct, essential activator of mTORC1: GTP-bound RHEB binds the mTOR catalytic domain at an allosteric site distal from the active site and triggers a global conformational change that accelerates kinase activity; this interaction is regulated by the TSC1/TSC2 GAP complex (which uses an asparagine-thumb mechanism to accelerate GTP hydrolysis), by upstream signaling (growth factors via Akt→TSC2 phosphorylation; amino acids via arginine-dependent TSC lysosomal displacement; energy stress via p38β-PRAK-mediated Ser130 phosphorylation of RHEB; ubiquitination by RNF152/deubiquitination by USP4); in addition to mTORC1 activation RHEB has mTOR-independent functions including inhibition of B-Raf/C-Raf, mTORC1-independent activation of PDH in mitochondria, disruption of dynein-cargo interactions to block aggresome formation, GTP-dependent destabilization of BACE1, PERK-mediated eIF2α phosphorylation, and PDE4D5 stabilization to suppress adipose beiging."},"narrative":{"mechanistic_narrative":"RHEB is a farnesylated Ras-family small GTPase that functions as the proximal, essential activator of mTOR complex 1 (mTORC1), positioned genetically downstream of the TSC1/TSC2 tumor suppressor complex and upstream of TOR/S6K to control cell and tissue growth [PMID:12869586, PMID:12842888, PMID:12766776, PMID:12766775, PMID:12893813]. GTP-bound RHEB binds directly to the mTOR catalytic domain (and LST8) independently of TSC2, and structural work shows it engages a site distal from the active site to drive a global conformational change that allosterically realigns active-site residues and accelerates catalysis; nucleotide-deficient RHEB still binds mTOR but traps it inactive [PMID:15854902, PMID:29236692]. RHEB is held in a constitutively high GTP-charged state, and its activity is set by the TSC2 GAP domain, which uses an 'asparagine thumb' (N1643) rather than a canonical arginine finger to stabilize the GTP γ-phosphate and accelerate hydrolysis [PMID:15340059, PMID:12214276, PMID:33436626]. This switch is integrated with upstream cues: amino acids/arginine and RNF152/USP4 ubiquitination control TSC–RHEB association and lysosomal positioning, while energy stress engages a p38β–PRAK cascade that phosphorylates RHEB at Ser130 to impair nucleotide binding [PMID:21336308, PMID:30514904, PMID:26742086]. RHEB requires C-terminal CAAX farnesylation (not geranylgeranylation) and Rce1/Icmt processing for ER/Golgi endomembrane localization, making it the critical farnesyltransferase-inhibitor target for mTOR pathway suppression [PMID:16046393, PMID:16006564]. Beyond mTORC1, RHEB has multiple mTOR-independent activities, including inhibition of B-Raf/C-Raf kinase activity and heterodimerization [PMID:15150271, PMID:16803888], mitochondrial activation of pyruvate dehydrogenase via PDP [PMID:33725483], GTP-dependent destabilization of BACE1 [PMID:24368770], and PERK-mediated eIF2α phosphorylation [PMID:25660019]. In vivo, RHEB is essential for embryonic cardiovascular development and growth [PMID:21321084], and a brain somatic gain-of-function mutation (p.Y35L) causes focal cortical dysplasia type II with seizures that are rescued by rapamycin [PMID:31337748].","teleology":[{"year":1994,"claim":"Established RHEB as a distinct Ras-family GTPase with intrinsic GTP-binding/hydrolysis activity and a farnesylation signal, providing the molecular starting point for all later mechanistic work.","evidence":"Differential cloning with bacterial fusion-protein GTPase assays and sequence analysis in activity-induced neurons","pmids":["8206940"],"confidence":"Medium","gaps":["No effector or pathway assigned at discovery","GTPase regulator (GAP/GEF) not identified"]},{"year":1997,"claim":"Distinguished RHEB from oncogenic Ras by showing it is farnesylated, non-transforming, and interacts differentially with Raf-1, hinting at a non-canonical Ras-like signaling role.","evidence":"In vitro/in vivo farnesylation assays, NIH 3T3 transformation assays, and Raf-1 co-IP with mutagenesis","pmids":["9099708","9001246"],"confidence":"Medium","gaps":["Physiological RHEB effector still unknown","Biological consequence of Raf-1 binding undefined"]},{"year":2002,"claim":"Showed RHEB is maintained in an unusually high GTP-bound state insensitive to growth conditions and inhibits B-Raf, framing it as a constitutively-active GTPase with a Raf-directed activity.","evidence":"GTP/GDP loading assays across three cell lines, endogenous B-Raf co-IP, kinase and Elk-1 reporter assays","pmids":["12214276"],"confidence":"Medium","gaps":["Did not connect RHEB to mTOR","Mechanism of constitutive GTP-loading unexplained"]},{"year":2003,"claim":"Placed RHEB in the TSC–mTOR axis by identifying TSC2 as a direct RHEB GAP and showing RHEB is rate-limiting for S6K/4EBP1 phosphorylation downstream of TSC1/TSC2 and upstream of mTOR.","evidence":"In vitro GAP assays, in vivo GTP-loading, genetic epistasis in mammalian cells and Drosophila, rapamycin/FTI sensitivity","pmids":["12869586","12842888","12766776","12766775","12893813","12214276"],"confidence":"High","gaps":["Direct RHEB–mTOR contact not yet demonstrated","How RHEB-GTP activates the kinase unknown"]},{"year":2004,"claim":"Defined the unusual catalytic chemistry of TSC2 GAP action (asparagine thumb, not arginine finger) and dissociated RHEB membrane targeting from its ability to drive S6K signaling.","evidence":"Site-directed mutagenesis with in vitro GAP and cell-based S6K assays","pmids":["15340059"],"confidence":"High","gaps":["Structural basis of the asparagine-thumb mechanism not yet resolved","Role of farnesylation in vivo left ambiguous"]},{"year":2005,"claim":"Demonstrated that RHEB binds the mTOR catalytic domain/LST8 directly and GTP-dependently to switch on kinase activity, identifying the long-sought RHEB–mTORC1 contact.","evidence":"Reciprocal co-IP, in vitro kinase assays with RHEB nucleotide and switch-I mutants, nucleotide-charging analysis","pmids":["15854902","15878852"],"confidence":"High","gaps":["Structural mechanism of activation unresolved","Whether an intermediate effector was required remained debated"]},{"year":2005,"claim":"Resolved the prenylation requirement of RHEB, showing it is exclusively farnesylated and traffics to ER/Golgi endomembranes via Rce1/Icmt processing, making RHEB the key farnesyltransferase-inhibitor target for mTOR blockade.","evidence":"In vitro prenylation with purified enzymes, Rce1/Icmt knockout imaging, FTI/GGTI treatment and geranylgeranylatable mutant rescue","pmids":["16046393","16006564"],"confidence":"High","gaps":["Functional role of endomembrane vs lysosomal pools not fully separated","How localization couples to mTOR activation unclear"]},{"year":2008,"claim":"Identified candidate RHEB effectors and broadened its mTOR-independent reach, proposing PLD1 as a GTP-dependent effector required for mTOR activation and linking RHEB to neuronal axon formation and dormant-tumor survival.","evidence":"In vitro PLD1 binding/activity assays, RNAi, neuronal overexpression/RNAi morphology, ATF6α/RHEB shRNA in a tumor dormancy model","pmids":["18550814","18842593","18650380"],"confidence":"Medium","gaps":["Relative contribution of PLD1 versus direct mTOR binding unresolved","Tissue-context dependence of effectors unclear"]},{"year":2009,"claim":"Reconstituted RHEB as a direct, specific GTP-dependent activator of raptor-containing mTORC1 in vitro and refuted FKBP38 as the obligate intermediary effector, settling the directness of RHEB–mTORC1 coupling.","evidence":"In vitro mTORC1 kinase assays with recombinant RHEB and effector-domain mutants; three independent in vitro assays failing to detect RHEB–FKBP38","pmids":["19299511","19222999","17991864"],"confidence":"High","gaps":["FKBP38 proposal (17991864) and its refutation reflect conflicting evidence","Mechanism of kinase acceleration still structurally undefined"]},{"year":2009,"claim":"Established a discrete mTOR-independent function in proteostasis, showing RHEB disrupts dynein–cargo interactions to block aggresome formation and sensitize cells to misfolded-protein death.","evidence":"TSC1/TSC2 knockout cells, RHEB perturbation, dynein–cargo co-IP, rapamycin controls","pmids":["19458266"],"confidence":"Medium","gaps":["Direct RHEB–dynein interaction not established","Single lab, single-readout proteostasis phenotype"]},{"year":2011,"claim":"Added a direct RHEB-targeted regulatory layer for energy stress, showing PRAK phosphorylates RHEB at Ser130 to impair nucleotide binding and inhibit mTORC1 independently of AMPK–TSC2.","evidence":"In vitro PRAK kinase assay, Ser130 mutagenesis, nucleotide-binding assay, p38β/PRAK depletion epistasis","pmids":["21336308"],"confidence":"High","gaps":["In vivo significance of Ser130 phosphorylation not established","Phosphatase reversing this mark unknown"]},{"year":2011,"claim":"Defined RHEB's organismal requirement, showing knockout is embryonic-lethal with impaired cardiovascular development and reduced TORC1 activity, and that Rheb heterozygosity rescues Tsc1-null embryos.","evidence":"Rheb knockout mice, embryonic fibroblast TORC1/cell-size assays, Tsc1/Rheb genetic epistasis","pmids":["21321084"],"confidence":"High","gaps":["Tissue-specific essential functions not dissected here","mTORC1-dependent versus -independent contributions to lethality unresolved"]},{"year":2015,"claim":"Mapped how nutrient and effector cues control the RHEB pool, identifying MCRS1 as a maintainer of lysosomal RHEB and an mTOR-independent PERK–eIF2α translational-suppression branch of RHEB signaling.","evidence":"siRNA/Cre-lox MEFs with RHEB localization and TSC2 co-IP; RHEB perturbation with PERK inhibition and eIF2α/protein-synthesis assays","pmids":["25816988","25660019"],"confidence":"Medium","gaps":["Mechanism by which MCRS1 retains RHEB at lysosomes unclear","Direct RHEB–PERK contact not demonstrated"]},{"year":2017,"claim":"Provided the near-atomic mechanism of mTORC1 activation, showing RHEB binds mTOR distally and drives an allosteric conformational change that realigns the active site, with cancer mutations mimicking RHEB's relief of autoinhibition.","evidence":"Cryo-EM of RHEB–mTORC1 (3.4 Å) and mTORC1 (3.0 Å) with crystal structures and in vitro kinase assays of cancer mutants","pmids":["29236692"],"confidence":"High","gaps":["Dynamics of the conformational transition not time-resolved","How upstream signals modulate this interface structurally not shown"]},{"year":2018,"claim":"Demonstrated RHEB switch II as a druggable surface, with the small molecule NR1 binding switch II to selectively block mTORC1 (S6K1) without inhibiting AKT/ERK or causing prolonged mTORC2 inhibition.","evidence":"NR1 binding assay, S6K1/AKT/ERK phosphorylation in cells, in vivo mouse mTORC1 assays, rapamycin comparison","pmids":["29416044"],"confidence":"Medium","gaps":["Co-structure of NR1–RHEB not reported here","Therapeutic window in disease models untested"]},{"year":2018,"claim":"Identified a ubiquitin-switch controlling RHEB–TSC association, with RNF152 ubiquitinating RHEB to favor TSC binding/inactivation and AKT-dependent USP4 deubiquitinating RHEB to release it for mTORC1 activation.","evidence":"Reciprocal co-IP, ubiquitination assays, RNF152/USP4 perturbation, AKT inhibition, mTORC1 assays","pmids":["30514904"],"confidence":"Medium","gaps":["Ubiquitinated RHEB residues not mapped","Single-lab pathway awaiting independent confirmation"]},{"year":2016,"claim":"Defined an amino-acid input acting through RHEB, showing arginine displaces the TSC complex from lysosomes and from RHEB to relieve allosteric inhibition and enable maximal growth-factor-driven mTORC1 activation.","evidence":"Lysosomal fractionation and TSC2–RHEB co-IP under arginine-replete/-depleted conditions across multiple cell types","pmids":["26742086"],"confidence":"High","gaps":["Arginine sensor upstream of TSC displacement not identified here","Quantitative coupling to RHEB GTP state not measured"]},{"year":2019,"claim":"Extended RHEB's biological reach in vivo, establishing it as a transcriptional ATF6 target driving cardiac hypertrophy and as an essential, amino-acid-coupled mTORC1 regulator for Treg cell suppressive identity.","evidence":"ChIP and cardiac-specific ATF6 KO with AAV9-RHEB rescue; Treg-specific Rheb1/Rheb2 double-KO mice with immune phenotyping","pmids":["30582446","31668641"],"confidence":"High","gaps":["Whether RHEB transcriptional induction is general or tissue-restricted unclear","Division of labor between Rheb1 and Rheb2 not resolved"]},{"year":2019,"claim":"Linked RHEB hyperactivation directly to human neurological disease, showing the brain somatic RHEB p.Y35L gain-of-function mutation causes focal cortical dysplasia type II with seizures rescued by rapamycin.","evidence":"Exome sequencing, GTPγS-binding and S6 phosphorylation assays, in utero electroporation mouse model with EEG and rapamycin treatment","pmids":["31337748"],"confidence":"High","gaps":["Spectrum of pathogenic RHEB mutations not defined","Cell-type origin of cytomegalic neurons not fully mapped"]},{"year":2021,"claim":"Resolved the TSC complex architecture and confirmed the catalytic GAP mechanism at the RHEB interface, showing a 2:2:1 TSC1:TSC2:TBC1D7 assembly in which the TSC2 asparagine thumb (N1643) stabilizes the GTP γ-phosphate.","evidence":"Cryo-EM of the human TSC complex with GAP-domain mutagenesis and biochemical assays","pmids":["33436626"],"confidence":"High","gaps":["Conformational coupling between TSC binding and RHEB nucleotide state not captured","How upstream signals remodel this complex on lysosomes unresolved"]},{"year":2021,"claim":"Defined a mitochondrial, mTOR-independent metabolic function, showing activity- and lactate-driven RHEB import via Tom20 activates pyruvate dehydrogenase through PDP, and that Schwann-cell RHEB loss impairs PDH and causes peripheral axon degeneration.","evidence":"Schwann-cell-specific Rheb KO and gain-of-function mice, mitochondrial fractionation, RHEB–Tom20 and RHEB–PDP co-IP, PDH activity and acetyl-CoA/ATP/lactate measurements, rapamycin controls","pmids":["33725483","34619097"],"confidence":"High","gaps":["How a farnesylated GTPase enters the matrix mechanistically unclear","Whether mitochondrial RHEB pool exists in non-neural tissues unknown"]},{"year":null,"claim":"It remains unresolved how the diverse upstream inputs (ubiquitination, Ser130 phosphorylation, arginine/TSC displacement, MCRS1) are quantitatively integrated to set RHEB's GTP state at the lysosome, and how a single farnesylated GTPase partitions between endomembrane mTORC1 activation and its distinct mTOR-independent functions (B-Raf inhibition, mitochondrial PDH activation, BACE1 destabilization, PERK signaling).","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model of RHEB GTP-state regulation across inputs","Spatial/temporal partitioning between mTOR-dependent and -independent pools undefined","Structural basis for non-mTOR effector engagement (PDP, B-Raf, BACE1) unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003924","term_label":"GTPase activity","supporting_discovery_ids":[0,2,5,32]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[3,18,26]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[3,11,14,16]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[12,21]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[12,21]},{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[28,31]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[33]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,3,18,26]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[3,18,29]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[33,34,37]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[42,30]}],"complexes":[],"partners":["MTOR","TSC2","BRAF","RAF1","PLD1","BACE1","PDP","TOM20"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q15382","full_name":"GTP-binding protein Rheb","aliases":["Ras homolog enriched in brain"],"length_aa":184,"mass_kda":20.5,"function":"Small GTPase that acts as an allosteric activator of the canonical mTORC1 complex, an evolutionarily conserved central nutrient sensor that stimulates anabolic reactions and macromolecule biosynthesis to promote cellular biomass generation and growth (PubMed:12172553, PubMed:12271141, PubMed:12842888, PubMed:12869586, PubMed:12906785, PubMed:15340059, PubMed:15854902, PubMed:16098514, PubMed:20381137, PubMed:22819219, PubMed:24529379, PubMed:29416044, PubMed:32470140, PubMed:33157014, PubMed:25816988). In response to nutrients, growth factors or amino acids, specifically activates the protein kinase activity of MTOR, the catalytic component of the mTORC1 complex: acts by causing a conformational change that allows the alignment of residues in the active site of MTOR, thereby enhancing the phosphorylation of ribosomal protein S6 kinase (RPS6KB1 and RPS6KB2) and EIF4EBP1 (4E-BP1) (PubMed:29236692, PubMed:33157014). RHEB is also required for localization of the TSC-TBC complex to lysosomal membranes (PubMed:24529379). In response to starvation, RHEB is inactivated by the TSC-TBC complex, preventing activation of mTORC1 (PubMed:24529379, PubMed:33157014). Has low intrinsic GTPase activity (PubMed:15340059)","subcellular_location":"Endomembrane system; Lysosome membrane; Golgi apparatus membrane; Endoplasmic reticulum membrane; Cytoplasm, cytosol","url":"https://www.uniprot.org/uniprotkb/Q15382/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RHEB","classification":"Not Classified","n_dependent_lines":556,"n_total_lines":1208,"dependency_fraction":0.4602649006622517},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000106615","cell_line_id":"CID000453","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"nucleoplasm","grade":3}],"interactors":[],"url":"https://opencell.sf.czbiohub.org/target/CID000453","total_profiled":1310},"omim":[{"mim_id":"618956","title":"RHEB-LIKE PROTEIN 1; RHEBL1","url":"https://www.omim.org/entry/618956"},{"mim_id":"615730","title":"DEDICATOR OF CYTOKINESIS 7; DOCK7","url":"https://www.omim.org/entry/615730"},{"mim_id":"612194","title":"RAS-RELATED GTP-BINDING PROTEIN A; RRAGA","url":"https://www.omim.org/entry/612194"},{"mim_id":"610221","title":"AKT1 SUBSTRATE 1, PROLINE-RICH; AKT1S1","url":"https://www.omim.org/entry/610221"},{"mim_id":"608268","title":"RAS-RELATED GTP-BINDING PROTEIN D; RRAGD","url":"https://www.omim.org/entry/608268"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/RHEB"},"hgnc":{"alias_symbol":[],"prev_symbol":["RHEB2"]},"alphafold":{"accession":"Q15382","domains":[{"cath_id":"3.40.50.300","chopping":"4-179","consensus_level":"high","plddt":93.8129,"start":4,"end":179}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q15382","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q15382-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q15382-F1-predicted_aligned_error_v6.png","plddt_mean":92.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RHEB","jax_strain_url":"https://www.jax.org/strain/search?query=RHEB"},"sequence":{"accession":"Q15382","fasta_url":"https://rest.uniprot.org/uniprotkb/Q15382.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q15382/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q15382"}},"corpus_meta":[{"pmid":"12869586","id":"PMC_12869586","title":"Rheb GTPase is a direct target of TSC2 GAP 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Rheb acts downstream of TSC1/TSC2 and upstream of mTOR.\",\n      \"method\": \"In vitro GAP activity assays, co-immunoprecipitation, dominant-negative and constitutively active mutant expression, genetic epistasis in mammalian cells\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — biochemical GAP assay plus genetic epistasis, independently replicated by multiple labs in the same year\",\n      \"pmids\": [\"12869586\", \"12842888\", \"12766776\", \"12766775\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Rheb is an essential regulator of S6 kinase (S6K) activity downstream of Tsc1/Tsc2 and upstream of TOR in Drosophila; loss-of-function Rheb mutations arrest larval growth and prevent G1-S progression, and overexpression promotes cell and tissue growth in a rapamycin-sensitive manner.\",\n      \"method\": \"Drosophila genetic screen, loss-of-function mutations, overexpression, rapamycin sensitivity assay\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with multiple alleles, replicated in two independent Drosophila studies\",\n      \"pmids\": [\"12766776\", \"12766775\", \"12893813\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"TSC2 GAP activity toward Rheb requires a catalytic 'asparagine thumb' (Asn residues in TSC2) rather than the arginine finger found in Ras-GAPs; Arg15 of Rheb (equivalent to Gly12 in Ras) is important for Rheb to serve as a TSC2 GAP substrate. Farnesylation and membrane localization of Rheb are not essential for Rheb to stimulate S6K phosphorylation.\",\n      \"method\": \"Site-directed mutagenesis, in vitro GAP activity assay, cell-based S6K phosphorylation assay\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of GAP activity with mutagenesis, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"15340059\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Rheb binds directly to the mTOR catalytic domain and to LST8 within mTOR complex 1 (TOR complex 1), independently of its ability to bind TSC2. Rheb-GTP binding enables activation of the TOR kinase; mTOR polypeptides bound to Rheb(Gln64Leu) (near-90% GTP-charged) exhibit substantially higher kinase activity, while nucleotide-deficient Rheb mutants bind mTOR but trap it in an inactive state.\",\n      \"method\": \"Co-immunoprecipitation (in vivo and in vitro), in vitro kinase assay, switch-I domain mutagenesis, nucleotide-charging analysis\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — reciprocal co-IP, in vitro kinase assay with multiple Rheb mutants, direct biochemical reconstitution\",\n      \"pmids\": [\"15854902\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Amino acid withdrawal reversibly inhibits binding of Rheb to endogenous and recombinant mTOR without altering Rheb GTP-charging. The inhibitory effect is exerted through an action on mTOR at a site largely distinct from the Rheb-binding region; deletion of the C-terminal lobe of the mTOR catalytic domain abolishes the inhibitory effect of amino acid withdrawal on Rheb binding.\",\n      \"method\": \"Co-immunoprecipitation, mTOR deletion mutants, GTP-charging assays, amino acid withdrawal/re-addition experiments\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple orthogonal methods in one study, direct biochemical measurement of Rheb-mTOR interaction under defined conditions\",\n      \"pmids\": [\"15878852\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"Rheb is a novel Ras-family small GTPase that binds and hydrolyzes GTP and contains a C-terminal CAAX box predicted to signal farnesylation for membrane targeting. It is rapidly and transiently induced in hippocampal neurons by seizures and NMDA-dependent synaptic activity.\",\n      \"method\": \"Differential cloning, bacterial fusion protein GTP-binding and GTPase activity assay, Northern blot, sequence analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — direct in vitro GTPase assay, single lab, original characterization paper\",\n      \"pmids\": [\"8206940\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Rheb is farnesylated in vitro and in vivo and is sensitive to farnesyltransferase inhibition. Unlike Ras, Rheb does not transform NIH 3T3 cells but instead antagonizes oncogenic Ras transformation and signaling, similar to KRev-1/Rap1A.\",\n      \"method\": \"In vitro and in vivo farnesylation assays, NIH 3T3 transformation assay, oncogenic Ras co-expression\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Weak — direct farnesylation assay and transformation assay, single lab\",\n      \"pmids\": [\"9099708\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Rheb interacts with Raf-1 kinase; unlike H-Ras, the Rheb-Raf-1 interaction is potentiated by growth factors combined with cAMP-elevating agents. Protein kinase A-dependent phosphorylation of Ser43 in Raf-1 reciprocally potentiates Raf-1 binding to Rheb and decreases its interaction with H-Ras. A single amino acid in the G2 effector domain is critical for the differential binding properties of Rheb versus Ras.\",\n      \"method\": \"Co-immunoprecipitation, mutagenesis, cAMP stimulation, PKA phosphorylation assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Weak — co-IP with mutagenesis, single lab\",\n      \"pmids\": [\"9001246\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Rheb is maintained in a high GTP-bound (activated) state in mammalian cells, much more so than Ras or Rap1, and its activation state is unaffected by changes in growth conditions. Rheb binds B-Raf kinase and inhibits B-Raf kinase activity and B-Raf-dependent Elk-1 transcriptional activation.\",\n      \"method\": \"GTP/GDP loading assays in three mammalian cell lines, co-immunoprecipitation of endogenous Rheb with B-Raf, in vitro kinase assay, Elk-1 reporter assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple cell lines, co-IP plus kinase assay, single lab\",\n      \"pmids\": [\"12214276\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"TSC2 binds Rheb-GTP in vitro and reduces Rheb GTP levels in vivo; overexpression of Rheb but not Rap1 promotes S6 kinase activation in a rapamycin-dependent manner. Rheb-mediated S6 phosphorylation is blocked by a farnesyl transferase inhibitor.\",\n      \"method\": \"In vitro pulldown (Rheb-GTP binding), in vivo GTP-loading assay, S6K phosphorylation assay, FTI treatment\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — biochemical binding assay combined with in vivo GTP loading and functional assay, replicated across labs\",\n      \"pmids\": [\"12842888\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Constitutive activation of the Rheb/mTOR/S6K cassette (by TSC1/TSC2 deletion or ectopic Rheb expression) is sufficient to induce insulin resistance by downregulating IRS1 and IRS2, rendering Akt refractory to activation by IRS-dependent growth factor pathways.\",\n      \"method\": \"Genetic deletion of TSC1/TSC2 in mouse embryonic fibroblasts, ectopic Rheb overexpression, Western blot for IRS1/IRS2 protein levels and Akt phosphorylation\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic deletion plus ectopic expression, multiple orthogonal readouts, single lab\",\n      \"pmids\": [\"15380067\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Rheb inhibits wild-type B-Raf kinase activity and this function is independent of mTOR/rapamycin (mTOR-independent). The interaction of endogenous Rheb with B-Raf is enhanced by serum and Ras overexpression. A farnesylation-defective Rheb mutant can still co-immunoprecipitate with and inhibit B-Raf, indicating that farnesylation is not required for B-Raf inhibition by Rheb. B-Raf inhibition and S6K activation are separable activities of Rheb.\",\n      \"method\": \"Co-immunoprecipitation, in vitro B-Raf kinase assay, rapamycin treatment, farnesylation-defective Rheb mutant\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (co-IP, kinase assay, mutagenesis), single lab\",\n      \"pmids\": [\"15150271\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Rheb localizes to endomembranes (endoplasmic reticulum, Golgi) rather than the plasma membrane, dependent on C-terminal CAAX farnesylation but not palmitoylation. Rce1 and Icmt post-prenylation processing steps are required for proper Rheb endomembrane localization; without the polybasic region or palmitoylation sites, Rheb diffusely localizes when Rce1 or Icmt are absent.\",\n      \"method\": \"Confocal microscopy with fluorescent protein fusions, Rce1 and Icmt knockout fibroblasts, farnesyltransferase and geranylgeranyltransferase inhibitors, CAAX cysteine mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct imaging in genetically defined knockout cells combined with pharmacological and mutagenesis controls, single lab with multiple orthogonal approaches\",\n      \"pmids\": [\"16046393\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Rheb farnesylation (via the C-terminal CAAX motif) is completely blocked by the FTI SCH66336 (lonafarnib) and Rheb is not alternatively geranylgeranylated. Rheb and Rheb2 C-terminal peptides are substrates for farnesyltransferase but not geranylgeranyltransferase-1 in vitro. FTI-mediated inhibition of mTOR/S6 signaling is reversed by a Rheb mutant engineered for geranylgeranylation, establishing Rheb as the critical FTI target for mTOR pathway inhibition.\",\n      \"method\": \"In vitro prenylation assay with purified enzymes, metabolic labeling in cell culture, S6 phosphorylation assay, Rheb CSVL geranylgeranylatable mutant rescue\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — direct in vitro prenylation assay combined with cell-based rescue experiments with specific mutant, single lab\",\n      \"pmids\": [\"16006564\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Rheb inhibits both B-Raf and C-Raf kinase activities and inhibits B-Raf/C-Raf heterodimerization; these effects are rapamycin-insensitive (mTOR-independent). Rheb activation is associated with decreased B-Raf (Ser-446) and C-Raf (Ser-338) phosphorylation and inhibits the association of B-Raf with H-Ras.\",\n      \"method\": \"In vitro kinase assay, co-immunoprecipitation of B-Raf/C-Raf heterodimers, rapamycin treatment\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple biochemical assays, single lab, consistent with prior findings\",\n      \"pmids\": [\"16803888\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Drosophila Rheb (dRheb) has an inhibitory effect on dTORC2 activity in Drosophila S2 cells; this appears to be mediated by a feedback mechanism involving dTORC1 and dS6K rather than direct Rheb-TORC2 interaction. Mammalian Rheb does not activate TORC2 in HEK293 cells. TSC1/TSC2 have opposite effects on TORC1 and TORC2.\",\n      \"method\": \"S2 cell RNAi, Akt and S6K phosphorylation as TORC2/TORC1 functional readouts, Drosophila genetics\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic and biochemical approaches in two cell systems, single lab\",\n      \"pmids\": [\"16627617\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Rheb activates mTOR by antagonizing FKBP38, an endogenous inhibitor of mTOR structurally related to FKBP12; Rheb interacts directly with FKBP38 in a GTP-dependent manner and prevents FKBP38 association with mTOR.\",\n      \"method\": \"Co-immunoprecipitation, in vitro binding assay, RNAi knockdown, mTOR kinase assay\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — co-IP and functional assay, single lab; note that subsequent work (PMID:19222999) failed to detect Rheb-FKBP38 interaction in vitro, creating contradictory evidence\",\n      \"pmids\": [\"17991864\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"The Rheb-FKBP38 interaction proposed in Science 2007 was not detected in three independent in vitro assay systems; cell biological experiments show FKBP38 plays only a very minor role, if any, in mTORC1 activation. FKBP38 is therefore not the long-sought Rheb effector linking Rheb to mTORC1 activation.\",\n      \"method\": \"Three independent in vitro binding assays, cell biological experiments\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple orthogonal in vitro assays explicitly refuting prior claim; recorded as negative finding\",\n      \"pmids\": [\"19222999\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Rheb specifically activates mTORC1 but not mTORC2 in a GTP-dependent manner in vitro; the activation requires the effector domain of Rheb and a raptor-containing mTORC1 complex. Rheb increases binding of the substrate 4E-BP1 to mTORC1. Other GTPases (KRas, RalA/B, Cdc42) do not activate mTORC1. Rheb does not induce mTOR autophosphorylation. FKBP38-depleted mTORC1 preparations are still activated by Rheb.\",\n      \"method\": \"In vitro mTORC1 kinase assay using immunoprecipitated mTORC1 from nutrient-starved cells, recombinant Rheb addition, effector domain mutants, substrate binding assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct in vitro reconstitution with multiple controls and mutants, single lab\",\n      \"pmids\": [\"19299511\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Rheb directly binds and activates PLD1 (but not PLD2) in a GTP-dependent manner in vitro, establishing PLD1 as a bona fide effector of Rheb. PLD1 is required (by RNAi) for Rheb activation of the mTOR pathway; TSC2 overexpression suppresses PLD1 activation, and TSC2 deletion elevates basal PLD activity.\",\n      \"method\": \"In vitro binding and PLD activity assay with recombinant proteins, RNAi knockdown, PLD activity assay, PI3K/AMPK pharmacological inhibitors\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct in vitro protein–protein interaction and enzyme activation assay, corroborated by RNAi in cells, single lab\",\n      \"pmids\": [\"18550814\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Rheb inhibits aggresome formation and sensitizes cells to death upon misfolded protein accumulation by disrupting the interaction between dynein and misfolded protein cargos, thereby blocking dynein-dependent retrograde transport. This function is independent of mTOR complex 1.\",\n      \"method\": \"Genetic TSC1/TSC2 knockout cells, Rheb overexpression/knockdown, co-immunoprecipitation of dynein with misfolded protein cargos, rapamycin treatment to distinguish mTOR-dependent from mTOR-independent effects\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic and biochemical approaches, rapamycin used to demonstrate mTOR independence, single lab\",\n      \"pmids\": [\"19458266\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Rheb localizes primarily to endoplasmic reticulum and Golgi apparatus (Rheb1 and Rheb2). Post-prenylation processing by Rce1 and Icmt is required for proper Rheb localization but dispensable for Rheb-induced activation of S6K; farnesylthiosalicylic acid (FTS) blocks S6K activation induced by constitutively active mTOR downstream of Rheb, suggesting FTS inhibits mTOR downstream of Rheb.\",\n      \"method\": \"Immunofluorescence microscopy, Rce1 and Icmt knockout cells, S6K phosphorylation assay, FTS treatment\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization in knockout cells combined with functional S6K assay, single lab\",\n      \"pmids\": [\"19838215\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PRAK (p38-regulated/activated kinase) directly phosphorylates Rheb at Ser130, which impairs the nucleotide-binding ability of Rheb and inhibits Rheb-mediated mTORC1 activation. This operates downstream of a p38β-PRAK cascade activated by energy starvation, independently of AMPK-mediated TSC2 and Raptor phosphorylation.\",\n      \"method\": \"In vitro kinase assay (PRAK phosphorylating Rheb), site-directed mutagenesis of Ser130, nucleotide binding assay, mTORC1 activity assay, PRAK/p38β depletion experiments\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct in vitro kinase assay with mutagenesis, nucleotide binding assay, and genetic epistasis, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"21336308\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Rheb overexpression induces multiple axon formation in hippocampal neurons via mTOR; Rheb suppression by RNAi blocks axon specification. mTOR acts through 4E-BP1 translation control; downstream of Rheb-mTOR, Rap1B levels are maintained by counteracting Smurf2-mediated degradation.\",\n      \"method\": \"Neuronal overexpression/RNAi in dissociated hippocampal neurons, morphological readout (axon number), rapamycin inhibition, 4E-BP1 mutant expression, Smurf2 RNAi rescue\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — epistasis via multiple RNAi and dominant constructs, direct morphological readout, single lab\",\n      \"pmids\": [\"18842593\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"ATF6α transcription factor induces Rheb expression, which activates mTOR signaling independently of Akt, promoting survival of quiescent/dormant tumor cells. Knockdown of ATF6α or Rheb reverts dormant tumor cell resistance to rapamycin.\",\n      \"method\": \"shRNA knockdown of ATF6α and Rheb, rapamycin treatment, in vivo dormancy model, mTOR activity assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockdown with in vivo validation and functional pathway epistasis, single lab\",\n      \"pmids\": [\"18650380\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Tsc2–Rheb signaling controls EphA receptor-dependent axon guidance; EphA receptor activation by ephrin-A ligands decreases ERK1/2-mediated inhibition of Tsc2, thereby inactivating the mTOR pathway. Tsc2 deficiency with hyperactive Rheb constitutively activates mTOR and inhibits ephrin-induced growth cone collapse.\",\n      \"method\": \"Tsc2 haploinsufficient mice (retinogeniculate projection analysis), ERK1/2 activity assay in neurons, growth cone collapse assay, mTOR activity assays\",\n      \"journal\": \"Nature neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic mouse model combined with cellular biochemical assays, multiple readouts, single lab\",\n      \"pmids\": [\"20062052\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Cryo-EM structure of RHEB-mTORC1 at 3.4 Å shows RHEB binds to mTOR distally from the kinase active site and causes a global conformational change that allosterically realigns active-site residues to accelerate catalysis. Cancer-associated hyperactivating mutations map to elements that maintain the inactive state and biochemically mimic RHEB relieving auto-inhibition.\",\n      \"method\": \"Cryo-EM structure determination (3.0 Å mTORC1; 3.4 Å RHEB-mTORC1), crystal structures of RAPTOR-TOS and mTOR FRB-substrate complexes, in vitro kinase assays, biochemical characterization of cancer mutations\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — near-atomic resolution cryo-EM structure with biochemical validation, defines allosteric activation mechanism\",\n      \"pmids\": [\"29236692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Ubiquitination of Rheb by the lysosome-anchored E3 ligase RNF152 promotes Rheb binding to the TSC complex and keeps Rheb inactive. EGF activates AKT-dependent phosphorylation of USP4, causing deubiquitination of Rheb and its release from the TSC complex, enabling mTORC1 activation.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, RNF152 and USP4 knockdown/overexpression, AKT inhibition, mTORC1 activity assays\",\n      \"journal\": \"Cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP with ubiquitination assay and genetic perturbations, single lab\",\n      \"pmids\": [\"30514904\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"MCRS1 is required for amino acid-dependent mTORC1 activation by maintaining Rheb at lysosome surfaces; MCRS1 suppression promotes Rheb/TSC2 interaction, renders Rheb inactive, and relocalizes Rheb from lysosomes to recycling endocytic vesicles.\",\n      \"method\": \"siRNA knockdown, inducible Cre/lox MEFs, co-immunoprecipitation (Rheb-TSC2, Rheb-MCRS1), immunofluorescence localization of Rheb\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus localization in two genetic systems, single lab\",\n      \"pmids\": [\"25816988\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Rheb inhibits protein synthesis by enhancing phosphorylation of eIF2α through activation of the ER kinase PERK, in a manner independent of mTORC1.\",\n      \"method\": \"Rheb overexpression and knockdown, eIF2α phosphorylation assays, PERK inhibition/knockdown, protein synthesis assays\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — functional assay with genetic perturbations, mTORC1 independence shown, single lab\",\n      \"pmids\": [\"25660019\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"GTP-bound Rheb interacts with BACE1 (β-secretase) and promotes its degradation through proteasomal and lysosomal pathways, independently of mTOR signaling. Rheb overexpression depletes BACE1 protein and reduces Aβ generation, while Rheb knockdown promotes BACE1 accumulation.\",\n      \"method\": \"Co-immunoprecipitation (GTP-Rheb with BACE1), proteasome and lysosome inhibitor experiments, Rheb overexpression/RNAi, Aβ measurement\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP combined with functional degradation assays and mTOR-independent demonstration, single lab\",\n      \"pmids\": [\"24368770\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Arginine suppresses lysosomal localization of the TSC complex and its interaction with Rheb, thereby relieving allosteric inhibition of Rheb by TSC and enabling maximal mTORC1 activation by growth factors. This mechanism does not involve regulation of mTORC1 lysosomal localization.\",\n      \"method\": \"Lysosomal fractionation, co-immunoprecipitation of TSC2 with Rheb under arginine-replete vs. -depleted conditions, mTORC1 activity assays in multiple cell types including hESC-derived lineages\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — lysosomal fractionation plus co-IP in multiple cell types, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"26742086\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Structural analysis at near-atomic resolution reveals the TSC complex has an arch-shaped 2:2:1 (TSC1:TSC2:TBC1D7) stoichiometry. Structural and biochemical analysis of the TSC2 GAP domain–Rheb interface confirms that the TSC2 asparagine thumb (N1643) stabilizes the γ-phosphate of GTP to accelerate Rheb GTP hydrolysis.\",\n      \"method\": \"Cryo-EM structure of human TSC complex, biochemical GAP activity assays, mutagenesis of catalytic residues\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — near-atomic resolution cryo-EM combined with biochemical mutagenesis, single study with multiple orthogonal methods\",\n      \"pmids\": [\"33436626\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Rheb is dynamically trafficked to the mitochondrial matrix through its interaction with Tom20 in response to neuronal activity and lactate. Mitochondria-localized Rheb activates pyruvate dehydrogenase (PDH) by physically associating with PDH phosphatase (PDP), enhancing PDP activity and its association with the catalytic E1α-subunit of PDH to reduce PDH phosphorylation and increase acetyl-CoA and ATP production. This function is independent of mTORC1.\",\n      \"method\": \"SC-specific Rheb knockout mice and gain-of-function models, mitochondrial fractionation, co-immunoprecipitation (Rheb-Tom20, Rheb-PDP), PDH activity assay, acetyl-CoA and ATP measurement, rapamycin comparison\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — direct biochemical interaction assay plus enzymatic activity assay with genetic models, mTORC1-independent function validated by rapamycin, single lab with multiple orthogonal approaches\",\n      \"pmids\": [\"33725483\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"SC-specific Rheb knockout suppresses pyruvate dehydrogenase (PDH) activity independently of mTORC1 and shifts pyruvate metabolism toward lactate production in Schwann cells, causing age-dependent peripheral axon degeneration.\",\n      \"method\": \"Schwann cell-specific Rheb knockout mice, PDH activity assay, lactate measurement, peripheral nerve function tests\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional knockout with biochemical and physiological phenotypic readouts, mTORC1 independence noted, single lab\",\n      \"pmids\": [\"34619097\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"ATF6 transcription factor directly transcriptionally induces RHEB expression (confirmed by chromatin immunoprecipitation) in cardiac myocytes, which activates mTORC1 to promote compensatory cardiac hypertrophy. ATF6 cardiac-specific knockout blunts hypertrophy and is rescued by ectopic RHEB.\",\n      \"method\": \"Chromatin immunoprecipitation (ATF6 on RHEB promoter), cardiac-specific ATF6 knockout mice (TAC and exercise models), AAV9-RHEB rescue, mTORC1 activity assays\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — ChIP identifies RHEB as direct ATF6 target, confirmed by conditional KO and rescue in vivo, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"30582446\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"A small molecule (NR1) binds Rheb in the switch II domain and selectively blocks mTORC1 signaling (inhibits S6K1 phosphorylation) without inhibiting AKT or ERK. Unlike rapamycin, NR1 does not cause prolonged mTORC2 inhibition. Rheb switch II domain point mutations that impair mTORC1 activation are mimicked by NR1 binding.\",\n      \"method\": \"Small molecule binding assay (NR1 binding to Rheb switch II), S6K1/AKT/ERK phosphorylation assays in cells, in vivo mouse kidney and muscle mTORC1 assay, comparison with rapamycin\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct biochemical binding to switch II domain with functional specificity assays in vitro and in vivo, single lab\",\n      \"pmids\": [\"29416044\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Rheb inhibits beiging of white adipose tissue through an mTORC1-independent mechanism involving stabilization of PDE4D5, which degrades cAMP and reduces PKA activity and UCP1 expression. Adipose-specific Rheb knockout increases cAMP, PKA activity, and UCP1; partial, but not complete, rescue by rapamycin confirms the mTORC1-independent component.\",\n      \"method\": \"Adipose-specific Rheb knockout mice, cAMP measurement, PKA activity assay, PDE4D5 protein stability assay, rapamycin treatment comparison, primary adipocyte overexpression\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional knockout with multiple biochemical readouts, mTORC1-independent mechanism supported by rapamycin partial rescue, single lab\",\n      \"pmids\": [\"28242620\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Rheb knockout mice die around midgestation, most likely due to impaired cardiovascular development; Rheb-null embryonic fibroblasts show decreased TORC1 activity, reduced cell size, and impaired proliferation. Rheb heterozygosity extends the lifespan of Tsc1-null embryos, establishing genetic interaction between Tsc1 and Rheb in vivo.\",\n      \"method\": \"Rheb knockout mouse generation, embryonic phenotype analysis, embryonic fibroblast TORC1 activity and cell size assays, Tsc1/Rheb double-mutant epistasis\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout mouse with biochemical and genetic epistasis validation, single lab\",\n      \"pmids\": [\"21321084\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In Treg cells, Rheb1 and Rheb2 (Rheb GTPases) are central regulators of amino acid-dependent mTORC1 activation; mice with Rheb1/Rheb2-deficient Treg cells develop fatal autoimmune disease with reduced effector Treg accumulation. Rheb1/Rheb2 enforce the eTreg cell suppressive gene signature, whereas Rag GTPases regulate mitochondrial and lysosomal fitness.\",\n      \"method\": \"Conditional Treg-specific Rheb1/Rheb2 double-knockout mice, mTORC1 activity assays, immune phenotyping, gene expression profiling\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional double-knockout mouse model with mTORC1 activity assays and defined autoimmune phenotype, single lab\",\n      \"pmids\": [\"31668641\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"NMR structure of Rheb-GDP shows the canonical Ras GTPase fold with GDP-dependent dynamics in the switch I and II regions. NMR revealed Ras effector-like binding of activated Rheb to the c-Raf Ras-binding domain (RBD) but with ~1000-fold lower affinity than Ras/RBD, suggesting lack of functional interaction with c-Raf.\",\n      \"method\": \"NMR structure determination of Rheb-GDP, NMR binding assay (Rheb to c-Raf RBD), affinity measurement\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — NMR structure with binding measurement, single study, negative result for functional Raf interaction recorded\",\n      \"pmids\": [\"20685651\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Rheb and raptor negatively regulate skeletal myogenic differentiation through suppression of IRS1; knockdown of Rheb enhances myogenic differentiation with increased Akt activation and elevated IRS1 protein levels and reduced IRS1 Ser307 phosphorylation. IRS1 knockdown eliminates the enhancement elicited by Rheb knockdown, placing IRS1 downstream of the Rheb-mTOR/raptor inhibitory pathway in myogenesis.\",\n      \"method\": \"C2C12 myoblast siRNA knockdown and overexpression, myogenic differentiation assays, IRS1/Akt phosphorylation Western blots, epistasis by IRS1 co-knockdown\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis in cell line with multiple perturbations, single lab\",\n      \"pmids\": [\"21852229\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Brain somatic doublet mutation RHEB p.Y35L increases Rheb GTPλS-binding activity, elevates mTOR/S6 phosphorylation in cells, and when expressed via in utero electroporation in mice causes cytomegalic neurons, dysregulated neuron migration, abnormal EEG, and seizures recapitulating focal cortical dysplasia type II; rapamycin rescues the EEG and seizure phenotype.\",\n      \"method\": \"Whole exome sequencing, GTPλS binding assay, in utero electroporation in mice, S6 phosphorylation assay, EEG recording, rapamycin treatment\",\n      \"journal\": \"Experimental & molecular medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — direct biochemical characterization of gain-of-function mutation combined with in vivo mouse model with pharmacological rescue, single lab\",\n      \"pmids\": [\"31337748\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RHEB is a farnesylated Ras-family small GTPase that is maintained in a predominantly GTP-bound state and functions as the direct, essential activator of mTORC1: GTP-bound RHEB binds the mTOR catalytic domain at an allosteric site distal from the active site and triggers a global conformational change that accelerates kinase activity; this interaction is regulated by the TSC1/TSC2 GAP complex (which uses an asparagine-thumb mechanism to accelerate GTP hydrolysis), by upstream signaling (growth factors via Akt→TSC2 phosphorylation; amino acids via arginine-dependent TSC lysosomal displacement; energy stress via p38β-PRAK-mediated Ser130 phosphorylation of RHEB; ubiquitination by RNF152/deubiquitination by USP4); in addition to mTORC1 activation RHEB has mTOR-independent functions including inhibition of B-Raf/C-Raf, mTORC1-independent activation of PDH in mitochondria, disruption of dynein-cargo interactions to block aggresome formation, GTP-dependent destabilization of BACE1, PERK-mediated eIF2α phosphorylation, and PDE4D5 stabilization to suppress adipose beiging.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RHEB is a farnesylated Ras-family small GTPase that functions as the proximal, essential activator of mTOR complex 1 (mTORC1), positioned genetically downstream of the TSC1/TSC2 tumor suppressor complex and upstream of TOR/S6K to control cell and tissue growth [#0, #1]. GTP-bound RHEB binds directly to the mTOR catalytic domain (and LST8) independently of TSC2, and structural work shows it engages a site distal from the active site to drive a global conformational change that allosterically realigns active-site residues and accelerates catalysis; nucleotide-deficient RHEB still binds mTOR but traps it inactive [#3, #26]. RHEB is held in a constitutively high GTP-charged state, and its activity is set by the TSC2 GAP domain, which uses an 'asparagine thumb' (N1643) rather than a canonical arginine finger to stabilize the GTP \\u03b3-phosphate and accelerate hydrolysis [#2, #8, #32]. This switch is integrated with upstream cues: amino acids/arginine and RNF152/USP4 ubiquitination control TSC\\u2013RHEB association and lysosomal positioning, while energy stress engages a p38\\u03b2\\u2013PRAK cascade that phosphorylates RHEB at Ser130 to impair nucleotide binding [#22, #27, #31]. RHEB requires C-terminal CAAX farnesylation (not geranylgeranylation) and Rce1/Icmt processing for ER/Golgi endomembrane localization, making it the critical farnesyltransferase-inhibitor target for mTOR pathway suppression [#12, #13]. Beyond mTORC1, RHEB has multiple mTOR-independent activities, including inhibition of B-Raf/C-Raf kinase activity and heterodimerization [#11, #14], mitochondrial activation of pyruvate dehydrogenase via PDP [#33], GTP-dependent destabilization of BACE1 [#30], and PERK-mediated eIF2\\u03b1 phosphorylation [#29]. In vivo, RHEB is essential for embryonic cardiovascular development and growth [#38], and a brain somatic gain-of-function mutation (p.Y35L) causes focal cortical dysplasia type II with seizures that are rescued by rapamycin [#42].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Established RHEB as a distinct Ras-family GTPase with intrinsic GTP-binding/hydrolysis activity and a farnesylation signal, providing the molecular starting point for all later mechanistic work.\",\n      \"evidence\": \"Differential cloning with bacterial fusion-protein GTPase assays and sequence analysis in activity-induced neurons\",\n      \"pmids\": [\"8206940\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No effector or pathway assigned at discovery\", \"GTPase regulator (GAP/GEF) not identified\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Distinguished RHEB from oncogenic Ras by showing it is farnesylated, non-transforming, and interacts differentially with Raf-1, hinting at a non-canonical Ras-like signaling role.\",\n      \"evidence\": \"In vitro/in vivo farnesylation assays, NIH 3T3 transformation assays, and Raf-1 co-IP with mutagenesis\",\n      \"pmids\": [\"9099708\", \"9001246\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological RHEB effector still unknown\", \"Biological consequence of Raf-1 binding undefined\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Showed RHEB is maintained in an unusually high GTP-bound state insensitive to growth conditions and inhibits B-Raf, framing it as a constitutively-active GTPase with a Raf-directed activity.\",\n      \"evidence\": \"GTP/GDP loading assays across three cell lines, endogenous B-Raf co-IP, kinase and Elk-1 reporter assays\",\n      \"pmids\": [\"12214276\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not connect RHEB to mTOR\", \"Mechanism of constitutive GTP-loading unexplained\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Placed RHEB in the TSC\\u2013mTOR axis by identifying TSC2 as a direct RHEB GAP and showing RHEB is rate-limiting for S6K/4EBP1 phosphorylation downstream of TSC1/TSC2 and upstream of mTOR.\",\n      \"evidence\": \"In vitro GAP assays, in vivo GTP-loading, genetic epistasis in mammalian cells and Drosophila, rapamycin/FTI sensitivity\",\n      \"pmids\": [\"12869586\", \"12842888\", \"12766776\", \"12766775\", \"12893813\", \"12214276\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct RHEB\\u2013mTOR contact not yet demonstrated\", \"How RHEB-GTP activates the kinase unknown\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Defined the unusual catalytic chemistry of TSC2 GAP action (asparagine thumb, not arginine finger) and dissociated RHEB membrane targeting from its ability to drive S6K signaling.\",\n      \"evidence\": \"Site-directed mutagenesis with in vitro GAP and cell-based S6K assays\",\n      \"pmids\": [\"15340059\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the asparagine-thumb mechanism not yet resolved\", \"Role of farnesylation in vivo left ambiguous\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Demonstrated that RHEB binds the mTOR catalytic domain/LST8 directly and GTP-dependently to switch on kinase activity, identifying the long-sought RHEB\\u2013mTORC1 contact.\",\n      \"evidence\": \"Reciprocal co-IP, in vitro kinase assays with RHEB nucleotide and switch-I mutants, nucleotide-charging analysis\",\n      \"pmids\": [\"15854902\", \"15878852\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural mechanism of activation unresolved\", \"Whether an intermediate effector was required remained debated\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Resolved the prenylation requirement of RHEB, showing it is exclusively farnesylated and traffics to ER/Golgi endomembranes via Rce1/Icmt processing, making RHEB the key farnesyltransferase-inhibitor target for mTOR blockade.\",\n      \"evidence\": \"In vitro prenylation with purified enzymes, Rce1/Icmt knockout imaging, FTI/GGTI treatment and geranylgeranylatable mutant rescue\",\n      \"pmids\": [\"16046393\", \"16006564\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional role of endomembrane vs lysosomal pools not fully separated\", \"How localization couples to mTOR activation unclear\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Identified candidate RHEB effectors and broadened its mTOR-independent reach, proposing PLD1 as a GTP-dependent effector required for mTOR activation and linking RHEB to neuronal axon formation and dormant-tumor survival.\",\n      \"evidence\": \"In vitro PLD1 binding/activity assays, RNAi, neuronal overexpression/RNAi morphology, ATF6\\u03b1/RHEB shRNA in a tumor dormancy model\",\n      \"pmids\": [\"18550814\", \"18842593\", \"18650380\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relative contribution of PLD1 versus direct mTOR binding unresolved\", \"Tissue-context dependence of effectors unclear\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Reconstituted RHEB as a direct, specific GTP-dependent activator of raptor-containing mTORC1 in vitro and refuted FKBP38 as the obligate intermediary effector, settling the directness of RHEB\\u2013mTORC1 coupling.\",\n      \"evidence\": \"In vitro mTORC1 kinase assays with recombinant RHEB and effector-domain mutants; three independent in vitro assays failing to detect RHEB\\u2013FKBP38\",\n      \"pmids\": [\"19299511\", \"19222999\", \"17991864\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"FKBP38 proposal (17991864) and its refutation reflect conflicting evidence\", \"Mechanism of kinase acceleration still structurally undefined\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Established a discrete mTOR-independent function in proteostasis, showing RHEB disrupts dynein\\u2013cargo interactions to block aggresome formation and sensitize cells to misfolded-protein death.\",\n      \"evidence\": \"TSC1/TSC2 knockout cells, RHEB perturbation, dynein\\u2013cargo co-IP, rapamycin controls\",\n      \"pmids\": [\"19458266\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct RHEB\\u2013dynein interaction not established\", \"Single lab, single-readout proteostasis phenotype\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Added a direct RHEB-targeted regulatory layer for energy stress, showing PRAK phosphorylates RHEB at Ser130 to impair nucleotide binding and inhibit mTORC1 independently of AMPK\\u2013TSC2.\",\n      \"evidence\": \"In vitro PRAK kinase assay, Ser130 mutagenesis, nucleotide-binding assay, p38\\u03b2/PRAK depletion epistasis\",\n      \"pmids\": [\"21336308\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo significance of Ser130 phosphorylation not established\", \"Phosphatase reversing this mark unknown\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined RHEB's organismal requirement, showing knockout is embryonic-lethal with impaired cardiovascular development and reduced TORC1 activity, and that Rheb heterozygosity rescues Tsc1-null embryos.\",\n      \"evidence\": \"Rheb knockout mice, embryonic fibroblast TORC1/cell-size assays, Tsc1/Rheb genetic epistasis\",\n      \"pmids\": [\"21321084\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-specific essential functions not dissected here\", \"mTORC1-dependent versus -independent contributions to lethality unresolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Mapped how nutrient and effector cues control the RHEB pool, identifying MCRS1 as a maintainer of lysosomal RHEB and an mTOR-independent PERK\\u2013eIF2\\u03b1 translational-suppression branch of RHEB signaling.\",\n      \"evidence\": \"siRNA/Cre-lox MEFs with RHEB localization and TSC2 co-IP; RHEB perturbation with PERK inhibition and eIF2\\u03b1/protein-synthesis assays\",\n      \"pmids\": [\"25816988\", \"25660019\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which MCRS1 retains RHEB at lysosomes unclear\", \"Direct RHEB\\u2013PERK contact not demonstrated\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Provided the near-atomic mechanism of mTORC1 activation, showing RHEB binds mTOR distally and drives an allosteric conformational change that realigns the active site, with cancer mutations mimicking RHEB's relief of autoinhibition.\",\n      \"evidence\": \"Cryo-EM of RHEB\\u2013mTORC1 (3.4 \\u00c5) and mTORC1 (3.0 \\u00c5) with crystal structures and in vitro kinase assays of cancer mutants\",\n      \"pmids\": [\"29236692\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Dynamics of the conformational transition not time-resolved\", \"How upstream signals modulate this interface structurally not shown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Demonstrated RHEB switch II as a druggable surface, with the small molecule NR1 binding switch II to selectively block mTORC1 (S6K1) without inhibiting AKT/ERK or causing prolonged mTORC2 inhibition.\",\n      \"evidence\": \"NR1 binding assay, S6K1/AKT/ERK phosphorylation in cells, in vivo mouse mTORC1 assays, rapamycin comparison\",\n      \"pmids\": [\"29416044\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Co-structure of NR1\\u2013RHEB not reported here\", \"Therapeutic window in disease models untested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified a ubiquitin-switch controlling RHEB\\u2013TSC association, with RNF152 ubiquitinating RHEB to favor TSC binding/inactivation and AKT-dependent USP4 deubiquitinating RHEB to release it for mTORC1 activation.\",\n      \"evidence\": \"Reciprocal co-IP, ubiquitination assays, RNF152/USP4 perturbation, AKT inhibition, mTORC1 assays\",\n      \"pmids\": [\"30514904\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Ubiquitinated RHEB residues not mapped\", \"Single-lab pathway awaiting independent confirmation\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Defined an amino-acid input acting through RHEB, showing arginine displaces the TSC complex from lysosomes and from RHEB to relieve allosteric inhibition and enable maximal growth-factor-driven mTORC1 activation.\",\n      \"evidence\": \"Lysosomal fractionation and TSC2\\u2013RHEB co-IP under arginine-replete/-depleted conditions across multiple cell types\",\n      \"pmids\": [\"26742086\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Arginine sensor upstream of TSC displacement not identified here\", \"Quantitative coupling to RHEB GTP state not measured\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Extended RHEB's biological reach in vivo, establishing it as a transcriptional ATF6 target driving cardiac hypertrophy and as an essential, amino-acid-coupled mTORC1 regulator for Treg cell suppressive identity.\",\n      \"evidence\": \"ChIP and cardiac-specific ATF6 KO with AAV9-RHEB rescue; Treg-specific Rheb1/Rheb2 double-KO mice with immune phenotyping\",\n      \"pmids\": [\"30582446\", \"31668641\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether RHEB transcriptional induction is general or tissue-restricted unclear\", \"Division of labor between Rheb1 and Rheb2 not resolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Linked RHEB hyperactivation directly to human neurological disease, showing the brain somatic RHEB p.Y35L gain-of-function mutation causes focal cortical dysplasia type II with seizures rescued by rapamycin.\",\n      \"evidence\": \"Exome sequencing, GTP\\u03b3S-binding and S6 phosphorylation assays, in utero electroporation mouse model with EEG and rapamycin treatment\",\n      \"pmids\": [\"31337748\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Spectrum of pathogenic RHEB mutations not defined\", \"Cell-type origin of cytomegalic neurons not fully mapped\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Resolved the TSC complex architecture and confirmed the catalytic GAP mechanism at the RHEB interface, showing a 2:2:1 TSC1:TSC2:TBC1D7 assembly in which the TSC2 asparagine thumb (N1643) stabilizes the GTP \\u03b3-phosphate.\",\n      \"evidence\": \"Cryo-EM of the human TSC complex with GAP-domain mutagenesis and biochemical assays\",\n      \"pmids\": [\"33436626\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Conformational coupling between TSC binding and RHEB nucleotide state not captured\", \"How upstream signals remodel this complex on lysosomes unresolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defined a mitochondrial, mTOR-independent metabolic function, showing activity- and lactate-driven RHEB import via Tom20 activates pyruvate dehydrogenase through PDP, and that Schwann-cell RHEB loss impairs PDH and causes peripheral axon degeneration.\",\n      \"evidence\": \"Schwann-cell-specific Rheb KO and gain-of-function mice, mitochondrial fractionation, RHEB\\u2013Tom20 and RHEB\\u2013PDP co-IP, PDH activity and acetyl-CoA/ATP/lactate measurements, rapamycin controls\",\n      \"pmids\": [\"33725483\", \"34619097\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How a farnesylated GTPase enters the matrix mechanistically unclear\", \"Whether mitochondrial RHEB pool exists in non-neural tissues unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how the diverse upstream inputs (ubiquitination, Ser130 phosphorylation, arginine/TSC displacement, MCRS1) are quantitatively integrated to set RHEB's GTP state at the lysosome, and how a single farnesylated GTPase partitions between endomembrane mTORC1 activation and its distinct mTOR-independent functions (B-Raf inhibition, mitochondrial PDH activation, BACE1 destabilization, PERK signaling).\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model of RHEB GTP-state regulation across inputs\", \"Spatial/temporal partitioning between mTOR-dependent and -independent pools undefined\", \"Structural basis for non-mTOR effector engagement (PDP, B-Raf, BACE1) unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003924\", \"supporting_discovery_ids\": [0, 2, 5, 32]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [3, 18, 26]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [3, 11, 14, 16]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [12, 21]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [12, 21]},\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [28, 31]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [33]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 3, 18, 26]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [3, 18, 29]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [33, 34, 37]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [42, 30]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"MTOR\", \"TSC2\", \"BRAF\", \"RAF1\", \"PLD1\", \"BACE1\", \"PDP\", \"TOM20\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}