{"gene":"TOB1","run_date":"2026-04-28T21:42:59","timeline":{"discoveries":[{"year":1996,"finding":"TOB1 (Tob) was identified as a protein that physically interacts with the receptor tyrosine kinase p185erbB2 (ErbB2) via its C-terminal half, and this interaction antagonizes Tob's anti-proliferative activity; the interaction was confirmed by co-immunoprecipitation and GST pulldown.","method":"GST pulldown, co-immunoprecipitation, cell growth suppression assay","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP plus GST pulldown with domain mapping, foundational discovery paper","pmids":["8632892"],"is_preprint":false},{"year":2000,"finding":"Tob associates with receptor-regulated Smads (Smad1, Smad5, Smad8) and colocalizes with them in nuclear bodies upon BMP2 stimulation; tob-deficient mice show increased bone mass and elevated BMP2-induced bone formation, and Tob overexpression represses BMP2-induced Smad-mediated transcriptional activation.","method":"Co-immunoprecipitation, immunolocalization, tob knockout mouse, transcriptional reporter assay","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP, genetic KO with specific phenotype, and transcriptional assay in same study; highly cited foundational paper","pmids":["11163184"],"is_preprint":false},{"year":2001,"finding":"In anergic T cells, Tob associates with Smad2 and Smad4 and enhances Smad DNA-binding at the −105 negative regulatory element of the IL-2 promoter, thereby suppressing IL-2 transcription independently of NFAT, AP-1, or NF-κB.","method":"Co-immunoprecipitation, EMSA/DNA-binding assay, antisense oligonucleotide knockdown, transcriptional reporter assay","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (Co-IP, EMSA, functional KD) in a single study","pmids":["11694881"],"is_preprint":false},{"year":1999,"finding":"The N-terminal half of Tob associates with hCaf1 (a component of the CCR4 transcription factor/deadenylase complex), and Caf1 associates with cyclin-dependent kinases; this interaction was shown for both Tob and Tob2.","method":"Co-immunoprecipitation, protein interaction assay","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP, single lab, but independently replicated across BTG/Tob family members","pmids":["10602502"],"is_preprint":false},{"year":2002,"finding":"Tob is phosphorylated at Ser152, Ser154, and Ser164 by Erk1 and Erk2 upon growth-factor stimulation; phosphorylation abolishes Tob's anti-proliferative function and suppression of cyclin D1 expression, placing Tob downstream of Erk and upstream of Rb in the G1 progression pathway.","method":"In vitro kinase assay, site-directed mutagenesis (Ser→Ala/Glu), tob−/− MEFs, cell cycle analysis","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1 — in vitro kinase assay with mutagenesis plus genetic KO validation, replicated by independent lab (PMID 12151396)","pmids":["12050114"],"is_preprint":false},{"year":2002,"finding":"ERK2 and JNK2 bind to and phosphorylate Tob in vitro; an ERK docking site resides in the N-terminal portion of Tob and phosphorylation sites in the C-terminal region; phosphomimetic Tob mutants show reduced anti-proliferative activity.","method":"Two-hybrid screen, in vitro kinase assay, cell cycle analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro kinase assay with domain mapping, corroborates PMID 12050114","pmids":["12151396"],"is_preprint":false},{"year":2001,"finding":"p90rsk1 associates with Tob in vitro and in vivo and phosphorylates Tob at least in vitro, suggesting that Tob function is regulated downstream of receptor tyrosine kinases via p90rsk1-mediated phosphorylation.","method":"In vitro kinase assay, co-immunoprecipitation","journal":"Genes to cells","confidence":"Medium","confidence_rationale":"Tier 1–2 — in vitro phosphorylation confirmed; in vivo association shown by Co-IP; single lab","pmids":["11260258"],"is_preprint":false},{"year":2003,"finding":"Tob acts as a transcriptional corepressor of the cyclin D1 promoter through interaction with histone deacetylase; tob−/− mice are predisposed to spontaneous tumor formation, and cyclin D1 mRNA is increased in tob−/− cells.","method":"tob−/− mouse tumor model, transcriptional reporter assay, co-immunoprecipitation with HDAC","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 — genetic KO with tumor phenotype, promoter assay, and Co-IP with HDAC; multiple methods in one study","pmids":["12756225"],"is_preprint":false},{"year":2003,"finding":"Tob interacts with inhibitory Smads 6 and 7 (identified by yeast two-hybrid), colocalizes with Smad6 at the plasma membrane, and enhances Smad6 interaction with activated BMP type I receptors, thereby cooperating with inhibitory Smads to suppress BMP signaling.","method":"Yeast two-hybrid, co-immunoprecipitation, immunolocalization, Xenopus embryo assay","journal":"Mechanisms of development","confidence":"High","confidence_rationale":"Tier 2 — yeast two-hybrid, Co-IP, functional in vivo Xenopus assay; multiple orthogonal methods","pmids":["12782279"],"is_preprint":false},{"year":2004,"finding":"Tob is a nuclear protein imported via a bipartite NLS (residues 18–40) and exported via an NES (residues 2–14); in oncogenic ErbB2-transformed cells nuclear export is facilitated, reducing anti-proliferative activity; mutation of the NLS impairs anti-proliferative function.","method":"GFP-tagged Tob localization, leptomycin B treatment, NLS/NES mutagenesis, cell cycle assay","journal":"Oncogene / Experimental cell research","confidence":"High","confidence_rationale":"Tier 2 — direct localization experiment with functional consequence via mutagenesis, replicated across two labs (PMIDs 15235587, 15051490)","pmids":["15235587","15051490"],"is_preprint":false},{"year":2005,"finding":"Tob interacts with poly(A)-binding protein (PABP) and inducible PABP (iPABP) via their C-terminal regions; Tob abrogates iPABP-enhanced translation of IL-2 mRNA in vitro, implicating Tob in translational suppression of IL-2 mRNA in anergic T cells.","method":"Expression library screen with GST-Tob, co-immunoprecipitation, GST pulldown, in vitro translation assay","journal":"Genes to cells","confidence":"High","confidence_rationale":"Tier 1–2 — GST pulldown with Co-IP and in vitro functional assay","pmids":["15676026"],"is_preprint":false},{"year":2006,"finding":"Tob1 is degraded via the ubiquitin-proteasome pathway through the SCF-Skp2 ubiquitin ligase complex; Skp2 interacts with Tob1 and facilitates its ubiquitination in vitro and in intact cells; Tob1 is stabilized in Skp2−/− fibroblasts.","method":"Co-immunoprecipitation, in vitro ubiquitination assay, Skp2 KO fibroblasts, Skp2 knockdown","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 1–2 — in vitro ubiquitination reconstitution plus genetic KO validation","pmids":["16951159"],"is_preprint":false},{"year":2002,"finding":"Tob and other BTG/Tob family members (BTG1, BTG2, Tob2) are degraded by the ubiquitin-proteasome system; the C-terminal regions are necessary and sufficient to confer instability, as demonstrated by proteasome inhibitor treatment and multiubiquitination assays.","method":"Proteasome inhibitor treatment, ubiquitin co-expression/immunoprecipitation, C-terminal truncation/fusion constructs","journal":"European journal of biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 — multiple constructs and ubiquitination assays; single lab","pmids":["12135500"],"is_preprint":false},{"year":2007,"finding":"Human TOB simultaneously interacts with the CCR4-CAF1 deadenylase complex and cytoplasmic PABPC1; this bridging interaction is required for TOB to enhance mRNA deadenylation in vivo; TOB colocalizes with P-bodies by immunofluorescence.","method":"GST pulldown, co-immunoprecipitation, mutagenesis, transcriptional pulsing mRNA decay assay, immunofluorescence","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods including functional mRNA decay assay and mutagenesis in single study","pmids":["17785442"],"is_preprint":false},{"year":2008,"finding":"Tob associates with the CCR4-NOT complex; the C-terminal half of Tob interacts with Cnot1 (core CCR4-NOT subunit) and the deadenylase activity of the complex is suppressed in vitro by Tob.","method":"Proteomics/co-immunoprecipitation, in vitro deadenylase activity assay","journal":"Cancer science","confidence":"Medium","confidence_rationale":"Tier 2 — proteomics plus in vitro enzymatic assay; single lab","pmids":["18377426"],"is_preprint":false},{"year":2009,"finding":"Crystal structure of the Tob N-terminal domain in complex with human Caf1 (hCaf1) revealed that Tob exhibits a novel fold and that both Box A and Box B of Tob mediate hCaf1 association; deadenylase activity of Caf1 is not required but complex formation with Caf1 is essential for cell growth inhibition.","method":"X-ray crystallography, cell growth assay with wild-type and mutant proteins","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — crystal structure plus functional mutagenesis validation","pmids":["19276069"],"is_preprint":false},{"year":2010,"finding":"NMR and biochemical analyses showed that Tob consists of a structured N-terminal BTG-Tob domain (binds Caf1) and an unstructured C-terminal region containing two PAM2 motifs (bind PABPC1 C-terminal PABC domain, Kd ~20 μM); competition between Tob and eRF3 for PABPC1 provides a thermodynamic mechanism for translation termination-coupled deadenylation.","method":"NMR spectroscopy, Western blot quantification, binding affinity measurement","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — NMR structural analysis with quantitative binding measurements","pmids":["20595394"],"is_preprint":false},{"year":2011,"finding":"Tob binds directly to CPEB3 via Tob's C-terminal unstructured region; Tob then recruits Caf1 deadenylase to form a ternary Tob-CPEB3-Caf1 complex, mediating CPEB3-accelerated mRNA deadenylation; dominant-negative Caf1 or Tob mutants abrogate this deadenylation.","method":"Co-immunoprecipitation, GST pulldown, in vitro deadenylation assay, dominant-negative mutant analysis","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1–2 — in vitro reconstitution of ternary complex, functional deadenylation assay, multiple orthogonal approaches","pmids":["21336257"],"is_preprint":false},{"year":2012,"finding":"The anti-proliferative activity of TOB1 (and BTG2) requires interaction with Caf1a (CNOT7) and Caf1b (CNOT8) deadenylase subunits; mutations abolishing this interaction eliminate anti-proliferative activity and effects on mRNA abundance and translation without requiring other CCR4-NOT subunits.","method":"Structure-guided mutagenesis, cell proliferation assay, siRNA knockdown of CCR4-NOT subunits, mRNA abundance and translation measurement","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 — mutagenesis combined with multiple cellular readouts; corroborates structural data from PMID 19276069","pmids":["23236473"],"is_preprint":false},{"year":2012,"finding":"TOB1 and TOB2 promote deadenylation by recruiting CAF1-CCR4 complex to mRNA 3' ends via simultaneous binding of CAF1 and PABP (recruitment model); TOBs' deadenylation-promoting and anti-proliferative activities are linked; phosphorylation of the three Erk sites does not affect deadenylation, indicating at least two independent mechanisms for cell growth arrest.","method":"mRNA tethering functional assay, biochemical analyses, mutagenesis","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1–2 — direct functional deadenylation assay with mutagenesis; establishes recruitment model","pmids":["22252318"],"is_preprint":false},{"year":2010,"finding":"Tob1 directly associates with Caf1 and with cyclin-dependent kinase 1 (Cdk1) and modulates Cdk1 kinase activity; Tob1 deletion increases hepatocyte proliferation and accelerates liver regeneration; Tob1 protein decreases after hepatectomy via post-transcriptional mechanisms.","method":"Co-immunoprecipitation, kinase activity assay, Tob1 KO mouse hepatectomy model","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 — Co-IP with kinase assay and genetic KO with specific in vivo phenotype","pmids":["20513747"],"is_preprint":false},{"year":2012,"finding":"UV irradiation promotes proteasome-dependent degradation of Tob; degradation-resistant Tob impairs UV-induced apoptosis while siRNA knockdown of Tob induces apoptosis independently of p53; Cul4-DDB1(Cdt2) mediates Tob ubiquitination, and Cdc7 phosphorylates Tob to inhibit this degradation, providing a pro-survival pathway after mild DNA damage.","method":"siRNA knockdown, Cul4/Cdc7 interaction and phosphorylation assays, tob−/− mice/MEFs, apoptosis assays","journal":"Oncogene / The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — genetic KO plus biochemical ubiquitination/phosphorylation assays; replicated across two papers","pmids":["18850001","23066029"],"is_preprint":false},{"year":2001,"finding":"PMA-induced phosphorylation of MARCKS increases MARCKS binding to Tob, displacing Tob from ErbB2 and leading to ErbB2 activation; the phosphorylation site domain (PSD) of MARCKS mediates its interaction with Tob.","method":"Co-immunoprecipitation, phorbol ester treatment, ErbB2 phosphorylation assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP with functional readout; single lab","pmids":["11327693"],"is_preprint":false},{"year":2005,"finding":"Tob1 and Tob2 proteins suppress steroid hormone receptor-dependent transcriptional activation in osteoblastic cells; Tob1 inhibits nuclear foci formation of dihydrotestosterone-bound androgen receptor as visualized by GFP-tagged AR live imaging.","method":"Luciferase reporter assay, confocal live imaging of GFP-AR, mutagenesis of LXXLL motif","journal":"Molecular and cellular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2–3 — functional reporter plus live imaging; single lab","pmids":["15664454"],"is_preprint":false},{"year":2015,"finding":"Tob1 and Tob2 inhibit proliferation of mouse embryonic stem cells by promoting degradation of Id3 mRNA; Tob1/Tob2 double-knockout ESCs grow faster without loss of pluripotency, and Id3 mRNA is a directly targeted transcript of the BMP4 signaling pathway.","method":"Tob1/2 knockout ESC lines, mRNA stability assay, cell proliferation assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO with specific mRNA decay phenotype; single lab","pmids":["25951976"],"is_preprint":false},{"year":2008,"finding":"TOB1 acts as a transcriptional co-activator of the Dpp2 promoter in concert with KLF2, linking two quiescence-maintenance factors to Dpp2 transcription in lymphocytes.","method":"Promoter-reporter (luciferase) assay","journal":"Molecular immunology","confidence":"Low","confidence_rationale":"Tier 3 — single reporter assay; single lab; no direct binding to Dpp2 promoter shown","pmids":["18555530"],"is_preprint":false},{"year":2014,"finding":"Arsenite-induced oxidative stress inhibits mRNA deadenylation primarily through proteolytic degradation of Tob and Pan3; siRNA knockdown of Tob and Pan3 recapitulates mRNA poly(A) tail stabilization, independent of eIF2α kinase HRI.","method":"siRNA knockdown, poly(A) tail length assay, Western blot","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — siRNA recapitulation experiment links Tob degradation to deadenylation inhibition; single lab","pmids":["25446091"],"is_preprint":false},{"year":2013,"finding":"Tob1 deficiency in CD4+ T cells is sufficient to drive aggressive experimental autoimmune encephalomyelitis (EAE); Tob1−/− Treg cells showed reduced regulatory function; reconstitution of Rag1−/− mice with Tob1−/− CD4+ T cells recapitulated the aggressive EAE phenotype.","method":"Tob1 KO mouse EAE model, T cell transfer into Rag1−/− mice, T cell phenotyping","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 — genetic KO with adoptive transfer experiment, defined cellular phenotype","pmids":["23797093"],"is_preprint":false},{"year":2021,"finding":"TOB1 associates with Smad4/5 to induce ID2 expression, which in turn restrains Th1/Th17 cell differentiation; Tob1−/− mice develop severe colitis, and Rag1−/− mice reconstituted with Tob1−/− T cells also develop severe colitis.","method":"Co-immunoprecipitation (Smad4/5), lentiviral overexpression/knockdown, RNA-seq, T cell transfer colitis model","journal":"Cellular and molecular gastroenterology and hepatology","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP plus genetic KO in vivo model; single lab","pmids":["34920145"],"is_preprint":false},{"year":1997,"finding":"Mouse Tob was cloned and shown to be ubiquitously expressed; like human Tob, mouse Tob contains proline/glutamine-rich sequences characteristic of transcription factors and has an ATTTA motif in the 3'-UTR typical of immediate-early genes, consistent with a role in response to extracellular signals.","method":"Molecular cloning, Northern blot, sequence analysis","journal":"Gene","confidence":"Low","confidence_rationale":"Tier 4 — sequence/expression characterization, no direct functional mechanism established","pmids":["9210596"],"is_preprint":false},{"year":2015,"finding":"Tob1 protein is localized to P-bodies (co-immunoprecipitation and co-localization with Dcp2) in round spermatids and oocytes, consistent with a post-transcriptional regulatory role in germ cells.","method":"Immunofluorescence, co-immunoprecipitation with Dcp2, RT-ddPCR expression profiling","journal":"Cell and tissue research","confidence":"Low","confidence_rationale":"Tier 3 — localization with Co-IP; no functional consequence demonstrated","pmids":["26662055"],"is_preprint":false}],"current_model":"TOB1 is an anti-proliferative scaffold protein that operates through at least two interconnected mechanisms: (1) in the nucleus, it acts as a transcriptional co-repressor by binding receptor-regulated Smads (Smad1/5/8) and inhibitory Smads (Smad6/7) to suppress BMP signaling, interacting with Smad2/4 to repress IL-2 transcription, and associating with HDAC to silence the cyclin D1 promoter; and (2) in the cytoplasm, it bridges PABPC1 and the CAF1 (CNOT7/8) subunit of the CCR4-NOT deadenylase complex via its C-terminal PAM2 motifs and N-terminal BTG domain respectively, thereby recruiting deadenylase activity to polyadenylated mRNAs and accelerating their decay, including specific targets via CPEB3. Its anti-proliferative activity is negatively regulated by ERK1/2-mediated phosphorylation at Ser152/154/164 and by SCF-Skp2- and Cul4-DDB1(Cdt2)-dependent ubiquitin-proteasomal degradation, while Cdc7 phosphorylation stabilizes Tob1 to promote cell survival after mild DNA damage. Nuclear localization depends on a bipartite NLS (residues 18–40) and is opposed by an NES (residues 2–14) that is activated in ErbB2-transformed cells."},"narrative":{"teleology":[{"year":1996,"claim":"Identification of TOB1 as an anti-proliferative protein that physically interacts with ErbB2 established the gene's foundational role as a growth suppressor regulated by receptor tyrosine kinase signaling.","evidence":"GST pulldown and co-immunoprecipitation with ErbB2, cell growth suppression assay in NIH3T3 cells","pmids":["8632892"],"confidence":"High","gaps":["Mechanism of anti-proliferative action unknown","Downstream targets not identified","Whether ErbB2 interaction is direct or indirect in vivo unclear"]},{"year":1999,"claim":"Discovery that TOB1 binds hCaf1, a deadenylase/transcription factor complex component, opened a second mechanistic axis beyond receptor tyrosine kinase interaction.","evidence":"Co-immunoprecipitation of Tob N-terminal domain with hCaf1","pmids":["10602502"],"confidence":"Medium","gaps":["Functional consequence of Caf1 interaction not demonstrated","No structural detail of binding interface","Role of Caf1 enzymatic activity in Tob function unknown"]},{"year":2000,"claim":"Demonstration that TOB1 associates with BMP-responsive Smads and that tob-knockout mice have increased bone mass established TOB1 as a physiological negative regulator of BMP/Smad signaling in bone.","evidence":"Co-immunoprecipitation with Smad1/5/8, tob−/− knockout mouse bone phenotype, BMP2-responsive reporter assay","pmids":["11163184"],"confidence":"High","gaps":["Whether Tob acts as a direct transcriptional corepressor at BMP-target promoters not shown","Mechanism of Smad-dependent repression unclear","Relationship between BMP suppression and anti-proliferative activity not delineated"]},{"year":2001,"claim":"Finding that TOB1 cooperates with Smad2/4 to repress IL-2 transcription in anergic T cells extended the Smad-dependent mechanism to adaptive immunity and identified a specific target gene.","evidence":"Co-immunoprecipitation with Smad2/4, EMSA at IL-2 promoter, antisense knockdown in anergic T cells","pmids":["11694881"],"confidence":"High","gaps":["Direct binding of Tob to the IL-2 promoter DNA not demonstrated","Post-transcriptional regulation of IL-2 not addressed","Role beyond T cell anergy not examined"]},{"year":2002,"claim":"Identification of ERK1/2-mediated phosphorylation at Ser152/154/164 as an inactivation mechanism resolved how mitogenic signaling overrides TOB1's growth-suppressive function, placing TOB1 in the ERK–cyclin D1–Rb pathway.","evidence":"In vitro kinase assays, Ser-to-Ala/Glu mutagenesis, tob−/− MEFs, cell cycle analysis; independently confirmed by two labs","pmids":["12050114","12151396"],"confidence":"High","gaps":["Whether phosphorylation disrupts specific protein interactions not determined","In vivo phosphorylation dynamics during cell cycle not tracked","Contribution of JNK2 phosphorylation versus ERK phosphorylation not resolved"]},{"year":2003,"claim":"Discovery that TOB1 recruits HDAC to repress the cyclin D1 promoter and that tob−/− mice develop spontaneous tumors established TOB1 as a bona fide tumor suppressor acting through chromatin modification.","evidence":"Tob−/− mouse tumor formation, cyclin D1 reporter assay, co-immunoprecipitation with HDAC","pmids":["12756225"],"confidence":"High","gaps":["Identity of specific HDAC isoform(s) not resolved","Whether HDAC recruitment is direct or Smad-mediated unknown","Tumor spectrum and penetrance not fully characterized"]},{"year":2003,"claim":"Identification of TOB1 interaction with inhibitory Smads 6/7, enhancing their association with BMP type I receptors, revealed a second mode of BMP pathway suppression at the receptor level.","evidence":"Yeast two-hybrid, co-immunoprecipitation, Xenopus embryo functional assay","pmids":["12782279"],"confidence":"High","gaps":["Relative contribution of R-Smad versus I-Smad mechanisms not quantified","Stoichiometry of Tob–Smad6 complex at the receptor unknown"]},{"year":2004,"claim":"Mapping of a bipartite NLS and CRM1-dependent NES demonstrated that TOB1's anti-proliferative function requires nuclear localization and that ErbB2-driven oncogenesis antagonizes this by promoting nuclear export.","evidence":"GFP-Tob localization with NLS/NES mutagenesis, leptomycin B treatment, cell cycle assays across two independent studies","pmids":["15235587","15051490"],"confidence":"High","gaps":["Signaling pathway from ErbB2 to NES activation not defined","Whether cytoplasmic Tob retains deadenylation function not tested"]},{"year":2006,"claim":"Identification of SCF-Skp2 as the E3 ligase targeting TOB1 for proteasomal degradation explained how TOB1 protein levels are controlled during cell cycle progression.","evidence":"In vitro ubiquitination reconstitution, Skp2−/− fibroblasts showing TOB1 stabilization, Skp2 knockdown","pmids":["16951159"],"confidence":"High","gaps":["Phosphodegron on Tob recognized by Skp2 not mapped","Interplay between Skp2 and Cul4-DDB1 pathways not clarified"]},{"year":2007,"claim":"Demonstration that TOB1 simultaneously bridges PABPC1 and the CAF1-CCR4 deadenylase to enhance mRNA deadenylation in vivo unified the Caf1-binding and PABP-binding activities into a coherent recruitment model for mRNA decay.","evidence":"GST pulldown, co-immunoprecipitation, transcriptional pulse-chase mRNA decay assay, P-body co-localization","pmids":["17785442"],"confidence":"High","gaps":["Specific mRNA targets not identified","Whether deadenylation is selective or global not determined","Structural basis of simultaneous bridging not resolved"]},{"year":2009,"claim":"Crystal structure of the TOB1 N-terminal domain bound to Caf1 revealed the atomic interface and showed that Caf1 complex formation, but not Caf1 deadenylase catalytic activity per se, is essential for growth inhibition.","evidence":"X-ray crystallography of Tob–hCaf1 complex, functional mutagenesis of interface residues","pmids":["19276069"],"confidence":"High","gaps":["Full-length Tob structure (including disordered C-terminus) unavailable","Whether Caf1 interaction scaffolds additional effectors beyond deadenylation not tested"]},{"year":2010,"claim":"NMR analysis revealing two PAM2 motifs in the disordered C-terminus binding PABPC1, competing with eRF3, provided a thermodynamic model for translation termination-coupled deadenylation mediated by TOB1.","evidence":"NMR spectroscopy, quantitative binding affinity measurements (Kd ~20 μM)","pmids":["20595394"],"confidence":"High","gaps":["Competition with eRF3 not validated in cells","Functional consequence of dual PAM2 motifs versus single motif not dissected"]},{"year":2011,"claim":"Discovery that TOB1 bridges CPEB3 and Caf1 into a ternary complex for target-specific mRNA deadenylation demonstrated that TOB1 can confer substrate selectivity on the deadenylase machinery.","evidence":"Co-immunoprecipitation, GST pulldown, in vitro deadenylation reconstitution, dominant-negative mutant analysis","pmids":["21336257"],"confidence":"High","gaps":["Full set of RNA-binding protein partners that confer selectivity not cataloged","In vivo mRNA targets of CPEB3–Tob pathway not identified genome-wide"]},{"year":2012,"claim":"Establishing that ERK phosphorylation of TOB1 does not affect its deadenylation-promoting activity revealed that TOB1 suppresses proliferation through at least two separable mechanisms: deadenylation and a phosphorylation-sensitive pathway.","evidence":"mRNA tethering functional assay, phosphomimetic mutagenesis, cell proliferation assays","pmids":["22252318","23236473"],"confidence":"High","gaps":["Identity of the phosphorylation-sensitive anti-proliferative mechanism unknown","Whether the two mechanisms converge on the same target mRNAs not tested"]},{"year":2012,"claim":"Identification of Cul4-DDB1(Cdt2) as a second E3 ligase for TOB1 and Cdc7 as a stabilizing kinase after UV damage revealed a DNA damage-responsive circuit where TOB1 stabilization promotes survival.","evidence":"Ubiquitination and phosphorylation assays, tob−/− MEFs, apoptosis assays after UV irradiation","pmids":["18850001","23066029"],"confidence":"High","gaps":["Cdt2 degron on Tob not precisely mapped","How Cdc7 phosphorylation blocks Cdt2 recognition structurally undefined","Relative contribution of Skp2 versus Cdt2 pathway in different contexts unknown"]},{"year":2013,"claim":"Demonstration that Tob1 deficiency in CD4+ T cells drives aggressive autoimmune encephalomyelitis and impairs Treg function established TOB1 as a critical checkpoint in T cell-mediated autoimmunity.","evidence":"Tob1−/− mice in EAE model, adoptive transfer of Tob1−/− CD4+ T cells into Rag1−/− recipients","pmids":["23797093"],"confidence":"High","gaps":["Molecular targets in Tregs responsible for functional impairment not identified","Whether deadenylation or Smad pathway underlies T cell phenotype unknown"]},{"year":null,"claim":"Major unresolved questions include the genome-wide identity of mRNAs selectively targeted by TOB1-mediated deadenylation, the structural basis for full-length TOB1 function, the relative contributions of transcriptional repression versus mRNA decay in each biological context, and the mechanism by which ERK phosphorylation impairs anti-proliferative activity independently of deadenylation.","evidence":"","pmids":[],"confidence":"Low","gaps":["No genome-wide CLIP or similar unbiased identification of TOB1 mRNA targets","No full-length TOB1 structure","Phosphorylation-sensitive anti-proliferative mechanism molecularly undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[13,16,17,19]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[1,2,7]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[8,18,19]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1,9]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[13,16]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[13,30]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,4,8]},{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[13,17,19]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[4,7,20]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[2,27,28]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[1,8]}],"complexes":["CCR4-NOT"],"partners":["CNOT7","CNOT8","PABPC1","SMAD1","SMAD4","ERBB2","CPEB3","SKP2"],"other_free_text":[]},"mechanistic_narrative":"TOB1 is an anti-proliferative scaffold protein that restrains cell growth through two interconnected mechanisms: transcriptional repression via Smad-dependent signaling and promotion of mRNA deadenylation via the CCR4-NOT complex. In the nucleus, TOB1 associates with receptor-regulated Smads (Smad1/5/8) to suppress BMP signaling and with Smad2/4 to repress IL-2 transcription, and it recruits HDAC to silence the cyclin D1 promoter, with tob-deficient mice exhibiting increased bone mass and predisposition to spontaneous tumors [PMID:11163184, PMID:11694881, PMID:12756225]. In the cytoplasm, its N-terminal BTG domain binds the CAF1 (CNOT7/CNOT8) deadenylase subunit while two C-terminal PAM2 motifs engage PABPC1, bridging the CCR4-NOT complex to polyadenylated mRNAs and accelerating their decay—an activity essential for its anti-proliferative function [PMID:17785442, PMID:19276069, PMID:23236473]. TOB1 anti-proliferative activity is negatively regulated by ERK1/2-mediated phosphorylation at Ser152/154/164 and by SCF-Skp2- and Cul4-DDB1(Cdt2)-dependent ubiquitin-proteasomal degradation, while Cdc7-mediated phosphorylation stabilizes TOB1 to promote cell survival after DNA damage [PMID:12050114, PMID:16951159, PMID:23066029]."},"prefetch_data":{"uniprot":{"accession":"P50616","full_name":"Protein Tob1","aliases":["Transducer of erbB-2 1"],"length_aa":345,"mass_kda":38.2,"function":"Anti-proliferative protein; the function is mediated by association with deadenylase subunits of the CCR4-NOT complex (PubMed:23236473, PubMed:8632892). Mediates CPEB3-accelerated mRNA deadenylation by binding to CPEB3 and recruiting CNOT7 which leads to target mRNA deadenylation and decay (PubMed:21336257)","subcellular_location":"Cytoplasm; Nucleus","url":"https://www.uniprot.org/uniprotkb/P50616/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TOB1","classification":"Not Classified","n_dependent_lines":5,"n_total_lines":1208,"dependency_fraction":0.0041390728476821195},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/TOB1","total_profiled":1310},"omim":[{"mim_id":"607396","title":"TRANSDUCER OF ERBB2, 2; TOB2","url":"https://www.omim.org/entry/607396"},{"mim_id":"605523","title":"TRANSDUCER OF ERBB2, 1; TOB1","url":"https://www.omim.org/entry/605523"},{"mim_id":"224700","title":"EBSTEIN 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Regulatory, integrative and comparative physiology","url":"https://pubmed.ncbi.nlm.nih.gov/11893628","citation_count":17,"is_preprint":false},{"pmid":"23066029","id":"PMC_23066029","title":"Inhibition of DNA damage-induced apoptosis through Cdc7-mediated stabilization of Tob.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23066029","citation_count":16,"is_preprint":false},{"pmid":"18555530","id":"PMC_18555530","title":"Lymphocyte quiescence factor Dpp2 is transcriptionally activated by KLF2 and TOB1.","date":"2008","source":"Molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/18555530","citation_count":16,"is_preprint":false},{"pmid":"17318539","id":"PMC_17318539","title":"Nitrite metabolism in Debaryomyces hansenii TOB-Y7, a yeast strain involved in tobacco fermentation.","date":"2007","source":"Applied microbiology and biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/17318539","citation_count":16,"is_preprint":false},{"pmid":"17164348","id":"PMC_17164348","title":"Twisted gastrulation (Tsg) is regulated by Tob and enhances TGF-beta signaling in activated T lymphocytes.","date":"2007","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/17164348","citation_count":15,"is_preprint":false},{"pmid":"33247598","id":"PMC_33247598","title":"Expression of TOB/BTG family members in patients with inflammatory bowel disease.","date":"2021","source":"Scandinavian journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/33247598","citation_count":15,"is_preprint":false},{"pmid":"12054157","id":"PMC_12054157","title":"Enhancing effect of Tob deficiency on bone formation is specific to bone morphogenetic protein-induced osteogenesis.","date":"2002","source":"Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research","url":"https://pubmed.ncbi.nlm.nih.gov/12054157","citation_count":15,"is_preprint":false},{"pmid":"31799657","id":"PMC_31799657","title":"Long non-coding RNA TOB1-AS1 modulates cell proliferation, apoptosis, migration and invasion through miR-23a/NEU1 axis via Wnt/b-catenin pathway in gastric cancer.","date":"2019","source":"European review for medical and pharmacological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/31799657","citation_count":15,"is_preprint":false},{"pmid":"33786619","id":"PMC_33786619","title":"Identification of miR‑25‑3p as a tumor biomarker: Regulation of cellular functions via TOB1 in breast cancer.","date":"2021","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/33786619","citation_count":14,"is_preprint":false},{"pmid":"30930080","id":"PMC_30930080","title":"The discovery of shorter synthetic proteolytic peptides derived from Tob1 protein.","date":"2019","source":"Peptides","url":"https://pubmed.ncbi.nlm.nih.gov/30930080","citation_count":13,"is_preprint":false},{"pmid":"18850001","id":"PMC_18850001","title":"Proteasome-mediated degradation of Tob is pivotal for triggering UV-induced apoptosis.","date":"2008","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/18850001","citation_count":12,"is_preprint":false},{"pmid":"26377349","id":"PMC_26377349","title":"Tob1 enhances radiosensitivity of breast cancer cells involving the JNK and p38 pathways.","date":"2015","source":"Cell biology international","url":"https://pubmed.ncbi.nlm.nih.gov/26377349","citation_count":12,"is_preprint":false},{"pmid":"24945807","id":"PMC_24945807","title":"Nfatc2 and Tob1 have non-overlapping function in T cell negative regulation and tumorigenesis.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24945807","citation_count":12,"is_preprint":false},{"pmid":"18657378","id":"PMC_18657378","title":"Tumor growth suppression by adenovirus-mediated introduction of a cell-growth-suppressing gene tob in a pancreatic cancer model.","date":"2008","source":"Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie","url":"https://pubmed.ncbi.nlm.nih.gov/18657378","citation_count":11,"is_preprint":false},{"pmid":"22797076","id":"PMC_22797076","title":"C. elegans FOG-3/Tob can either promote or inhibit germline proliferation, depending on gene dosage and genetic context.","date":"2012","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/22797076","citation_count":11,"is_preprint":false},{"pmid":"25446091","id":"PMC_25446091","title":"Arsenite inhibits mRNA deadenylation through proteolytic degradation of Tob and Pan3.","date":"2014","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/25446091","citation_count":10,"is_preprint":false},{"pmid":"23756562","id":"PMC_23756562","title":"Overexpression of TOB1 confers radioprotection to bronchial epithelial cells through the MAPK/ERK pathway.","date":"2013","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/23756562","citation_count":10,"is_preprint":false},{"pmid":"26662055","id":"PMC_26662055","title":"Tob1 is expressed in developing and adult gonads and is associated with the P-body marker, Dcp2.","date":"2015","source":"Cell and tissue research","url":"https://pubmed.ncbi.nlm.nih.gov/26662055","citation_count":9,"is_preprint":false},{"pmid":"35465266","id":"PMC_35465266","title":"The Overexpression of TOB1 Induces Autophagy in Gastric Cancer Cells by Secreting Exosomes.","date":"2022","source":"Disease markers","url":"https://pubmed.ncbi.nlm.nih.gov/35465266","citation_count":9,"is_preprint":false},{"pmid":"35186488","id":"PMC_35186488","title":"Involvement of TOB1 on autophagy in gastric cancer AGS cells via decreasing the activation of AKT/mTOR signaling pathway.","date":"2022","source":"PeerJ","url":"https://pubmed.ncbi.nlm.nih.gov/35186488","citation_count":9,"is_preprint":false},{"pmid":"31891232","id":"PMC_31891232","title":"TOB1 suppresses proliferation in K-Ras wild-type pancreatic cancer.","date":"2019","source":"Cancer medicine","url":"https://pubmed.ncbi.nlm.nih.gov/31891232","citation_count":9,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":47674,"output_tokens":6827,"usd":0.122714},"stage2":{"model":"claude-opus-4-6","input_tokens":10645,"output_tokens":4000,"usd":0.229838},"total_usd":0.352552,"stage1_batch_id":"msgbatch_01RPbVc9PDH9zQmYK5Hs6srm","stage2_batch_id":"msgbatch_01JVbVLzeKN2yVrsGp3zC8aM","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1996,\n      \"finding\": \"TOB1 (Tob) was identified as a protein that physically interacts with the receptor tyrosine kinase p185erbB2 (ErbB2) via its C-terminal half, and this interaction antagonizes Tob's anti-proliferative activity; the interaction was confirmed by co-immunoprecipitation and GST pulldown.\",\n      \"method\": \"GST pulldown, co-immunoprecipitation, cell growth suppression assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus GST pulldown with domain mapping, foundational discovery paper\",\n      \"pmids\": [\"8632892\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Tob associates with receptor-regulated Smads (Smad1, Smad5, Smad8) and colocalizes with them in nuclear bodies upon BMP2 stimulation; tob-deficient mice show increased bone mass and elevated BMP2-induced bone formation, and Tob overexpression represses BMP2-induced Smad-mediated transcriptional activation.\",\n      \"method\": \"Co-immunoprecipitation, immunolocalization, tob knockout mouse, transcriptional reporter assay\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP, genetic KO with specific phenotype, and transcriptional assay in same study; highly cited foundational paper\",\n      \"pmids\": [\"11163184\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"In anergic T cells, Tob associates with Smad2 and Smad4 and enhances Smad DNA-binding at the −105 negative regulatory element of the IL-2 promoter, thereby suppressing IL-2 transcription independently of NFAT, AP-1, or NF-κB.\",\n      \"method\": \"Co-immunoprecipitation, EMSA/DNA-binding assay, antisense oligonucleotide knockdown, transcriptional reporter assay\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (Co-IP, EMSA, functional KD) in a single study\",\n      \"pmids\": [\"11694881\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"The N-terminal half of Tob associates with hCaf1 (a component of the CCR4 transcription factor/deadenylase complex), and Caf1 associates with cyclin-dependent kinases; this interaction was shown for both Tob and Tob2.\",\n      \"method\": \"Co-immunoprecipitation, protein interaction assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP, single lab, but independently replicated across BTG/Tob family members\",\n      \"pmids\": [\"10602502\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Tob is phosphorylated at Ser152, Ser154, and Ser164 by Erk1 and Erk2 upon growth-factor stimulation; phosphorylation abolishes Tob's anti-proliferative function and suppression of cyclin D1 expression, placing Tob downstream of Erk and upstream of Rb in the G1 progression pathway.\",\n      \"method\": \"In vitro kinase assay, site-directed mutagenesis (Ser→Ala/Glu), tob−/− MEFs, cell cycle analysis\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro kinase assay with mutagenesis plus genetic KO validation, replicated by independent lab (PMID 12151396)\",\n      \"pmids\": [\"12050114\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"ERK2 and JNK2 bind to and phosphorylate Tob in vitro; an ERK docking site resides in the N-terminal portion of Tob and phosphorylation sites in the C-terminal region; phosphomimetic Tob mutants show reduced anti-proliferative activity.\",\n      \"method\": \"Two-hybrid screen, in vitro kinase assay, cell cycle analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro kinase assay with domain mapping, corroborates PMID 12050114\",\n      \"pmids\": [\"12151396\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"p90rsk1 associates with Tob in vitro and in vivo and phosphorylates Tob at least in vitro, suggesting that Tob function is regulated downstream of receptor tyrosine kinases via p90rsk1-mediated phosphorylation.\",\n      \"method\": \"In vitro kinase assay, co-immunoprecipitation\",\n      \"journal\": \"Genes to cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro phosphorylation confirmed; in vivo association shown by Co-IP; single lab\",\n      \"pmids\": [\"11260258\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Tob acts as a transcriptional corepressor of the cyclin D1 promoter through interaction with histone deacetylase; tob−/− mice are predisposed to spontaneous tumor formation, and cyclin D1 mRNA is increased in tob−/− cells.\",\n      \"method\": \"tob−/− mouse tumor model, transcriptional reporter assay, co-immunoprecipitation with HDAC\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with tumor phenotype, promoter assay, and Co-IP with HDAC; multiple methods in one study\",\n      \"pmids\": [\"12756225\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Tob interacts with inhibitory Smads 6 and 7 (identified by yeast two-hybrid), colocalizes with Smad6 at the plasma membrane, and enhances Smad6 interaction with activated BMP type I receptors, thereby cooperating with inhibitory Smads to suppress BMP signaling.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, immunolocalization, Xenopus embryo assay\",\n      \"journal\": \"Mechanisms of development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — yeast two-hybrid, Co-IP, functional in vivo Xenopus assay; multiple orthogonal methods\",\n      \"pmids\": [\"12782279\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Tob is a nuclear protein imported via a bipartite NLS (residues 18–40) and exported via an NES (residues 2–14); in oncogenic ErbB2-transformed cells nuclear export is facilitated, reducing anti-proliferative activity; mutation of the NLS impairs anti-proliferative function.\",\n      \"method\": \"GFP-tagged Tob localization, leptomycin B treatment, NLS/NES mutagenesis, cell cycle assay\",\n      \"journal\": \"Oncogene / Experimental cell research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct localization experiment with functional consequence via mutagenesis, replicated across two labs (PMIDs 15235587, 15051490)\",\n      \"pmids\": [\"15235587\", \"15051490\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Tob interacts with poly(A)-binding protein (PABP) and inducible PABP (iPABP) via their C-terminal regions; Tob abrogates iPABP-enhanced translation of IL-2 mRNA in vitro, implicating Tob in translational suppression of IL-2 mRNA in anergic T cells.\",\n      \"method\": \"Expression library screen with GST-Tob, co-immunoprecipitation, GST pulldown, in vitro translation assay\",\n      \"journal\": \"Genes to cells\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — GST pulldown with Co-IP and in vitro functional assay\",\n      \"pmids\": [\"15676026\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Tob1 is degraded via the ubiquitin-proteasome pathway through the SCF-Skp2 ubiquitin ligase complex; Skp2 interacts with Tob1 and facilitates its ubiquitination in vitro and in intact cells; Tob1 is stabilized in Skp2−/− fibroblasts.\",\n      \"method\": \"Co-immunoprecipitation, in vitro ubiquitination assay, Skp2 KO fibroblasts, Skp2 knockdown\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro ubiquitination reconstitution plus genetic KO validation\",\n      \"pmids\": [\"16951159\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Tob and other BTG/Tob family members (BTG1, BTG2, Tob2) are degraded by the ubiquitin-proteasome system; the C-terminal regions are necessary and sufficient to confer instability, as demonstrated by proteasome inhibitor treatment and multiubiquitination assays.\",\n      \"method\": \"Proteasome inhibitor treatment, ubiquitin co-expression/immunoprecipitation, C-terminal truncation/fusion constructs\",\n      \"journal\": \"European journal of biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple constructs and ubiquitination assays; single lab\",\n      \"pmids\": [\"12135500\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Human TOB simultaneously interacts with the CCR4-CAF1 deadenylase complex and cytoplasmic PABPC1; this bridging interaction is required for TOB to enhance mRNA deadenylation in vivo; TOB colocalizes with P-bodies by immunofluorescence.\",\n      \"method\": \"GST pulldown, co-immunoprecipitation, mutagenesis, transcriptional pulsing mRNA decay assay, immunofluorescence\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods including functional mRNA decay assay and mutagenesis in single study\",\n      \"pmids\": [\"17785442\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Tob associates with the CCR4-NOT complex; the C-terminal half of Tob interacts with Cnot1 (core CCR4-NOT subunit) and the deadenylase activity of the complex is suppressed in vitro by Tob.\",\n      \"method\": \"Proteomics/co-immunoprecipitation, in vitro deadenylase activity assay\",\n      \"journal\": \"Cancer science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — proteomics plus in vitro enzymatic assay; single lab\",\n      \"pmids\": [\"18377426\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Crystal structure of the Tob N-terminal domain in complex with human Caf1 (hCaf1) revealed that Tob exhibits a novel fold and that both Box A and Box B of Tob mediate hCaf1 association; deadenylase activity of Caf1 is not required but complex formation with Caf1 is essential for cell growth inhibition.\",\n      \"method\": \"X-ray crystallography, cell growth assay with wild-type and mutant proteins\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure plus functional mutagenesis validation\",\n      \"pmids\": [\"19276069\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"NMR and biochemical analyses showed that Tob consists of a structured N-terminal BTG-Tob domain (binds Caf1) and an unstructured C-terminal region containing two PAM2 motifs (bind PABPC1 C-terminal PABC domain, Kd ~20 μM); competition between Tob and eRF3 for PABPC1 provides a thermodynamic mechanism for translation termination-coupled deadenylation.\",\n      \"method\": \"NMR spectroscopy, Western blot quantification, binding affinity measurement\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — NMR structural analysis with quantitative binding measurements\",\n      \"pmids\": [\"20595394\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Tob binds directly to CPEB3 via Tob's C-terminal unstructured region; Tob then recruits Caf1 deadenylase to form a ternary Tob-CPEB3-Caf1 complex, mediating CPEB3-accelerated mRNA deadenylation; dominant-negative Caf1 or Tob mutants abrogate this deadenylation.\",\n      \"method\": \"Co-immunoprecipitation, GST pulldown, in vitro deadenylation assay, dominant-negative mutant analysis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro reconstitution of ternary complex, functional deadenylation assay, multiple orthogonal approaches\",\n      \"pmids\": [\"21336257\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The anti-proliferative activity of TOB1 (and BTG2) requires interaction with Caf1a (CNOT7) and Caf1b (CNOT8) deadenylase subunits; mutations abolishing this interaction eliminate anti-proliferative activity and effects on mRNA abundance and translation without requiring other CCR4-NOT subunits.\",\n      \"method\": \"Structure-guided mutagenesis, cell proliferation assay, siRNA knockdown of CCR4-NOT subunits, mRNA abundance and translation measurement\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — mutagenesis combined with multiple cellular readouts; corroborates structural data from PMID 19276069\",\n      \"pmids\": [\"23236473\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"TOB1 and TOB2 promote deadenylation by recruiting CAF1-CCR4 complex to mRNA 3' ends via simultaneous binding of CAF1 and PABP (recruitment model); TOBs' deadenylation-promoting and anti-proliferative activities are linked; phosphorylation of the three Erk sites does not affect deadenylation, indicating at least two independent mechanisms for cell growth arrest.\",\n      \"method\": \"mRNA tethering functional assay, biochemical analyses, mutagenesis\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct functional deadenylation assay with mutagenesis; establishes recruitment model\",\n      \"pmids\": [\"22252318\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Tob1 directly associates with Caf1 and with cyclin-dependent kinase 1 (Cdk1) and modulates Cdk1 kinase activity; Tob1 deletion increases hepatocyte proliferation and accelerates liver regeneration; Tob1 protein decreases after hepatectomy via post-transcriptional mechanisms.\",\n      \"method\": \"Co-immunoprecipitation, kinase activity assay, Tob1 KO mouse hepatectomy model\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP with kinase assay and genetic KO with specific in vivo phenotype\",\n      \"pmids\": [\"20513747\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"UV irradiation promotes proteasome-dependent degradation of Tob; degradation-resistant Tob impairs UV-induced apoptosis while siRNA knockdown of Tob induces apoptosis independently of p53; Cul4-DDB1(Cdt2) mediates Tob ubiquitination, and Cdc7 phosphorylates Tob to inhibit this degradation, providing a pro-survival pathway after mild DNA damage.\",\n      \"method\": \"siRNA knockdown, Cul4/Cdc7 interaction and phosphorylation assays, tob−/− mice/MEFs, apoptosis assays\",\n      \"journal\": \"Oncogene / The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO plus biochemical ubiquitination/phosphorylation assays; replicated across two papers\",\n      \"pmids\": [\"18850001\", \"23066029\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"PMA-induced phosphorylation of MARCKS increases MARCKS binding to Tob, displacing Tob from ErbB2 and leading to ErbB2 activation; the phosphorylation site domain (PSD) of MARCKS mediates its interaction with Tob.\",\n      \"method\": \"Co-immunoprecipitation, phorbol ester treatment, ErbB2 phosphorylation assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP with functional readout; single lab\",\n      \"pmids\": [\"11327693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Tob1 and Tob2 proteins suppress steroid hormone receptor-dependent transcriptional activation in osteoblastic cells; Tob1 inhibits nuclear foci formation of dihydrotestosterone-bound androgen receptor as visualized by GFP-tagged AR live imaging.\",\n      \"method\": \"Luciferase reporter assay, confocal live imaging of GFP-AR, mutagenesis of LXXLL motif\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — functional reporter plus live imaging; single lab\",\n      \"pmids\": [\"15664454\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Tob1 and Tob2 inhibit proliferation of mouse embryonic stem cells by promoting degradation of Id3 mRNA; Tob1/Tob2 double-knockout ESCs grow faster without loss of pluripotency, and Id3 mRNA is a directly targeted transcript of the BMP4 signaling pathway.\",\n      \"method\": \"Tob1/2 knockout ESC lines, mRNA stability assay, cell proliferation assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with specific mRNA decay phenotype; single lab\",\n      \"pmids\": [\"25951976\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"TOB1 acts as a transcriptional co-activator of the Dpp2 promoter in concert with KLF2, linking two quiescence-maintenance factors to Dpp2 transcription in lymphocytes.\",\n      \"method\": \"Promoter-reporter (luciferase) assay\",\n      \"journal\": \"Molecular immunology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single reporter assay; single lab; no direct binding to Dpp2 promoter shown\",\n      \"pmids\": [\"18555530\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Arsenite-induced oxidative stress inhibits mRNA deadenylation primarily through proteolytic degradation of Tob and Pan3; siRNA knockdown of Tob and Pan3 recapitulates mRNA poly(A) tail stabilization, independent of eIF2α kinase HRI.\",\n      \"method\": \"siRNA knockdown, poly(A) tail length assay, Western blot\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — siRNA recapitulation experiment links Tob degradation to deadenylation inhibition; single lab\",\n      \"pmids\": [\"25446091\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Tob1 deficiency in CD4+ T cells is sufficient to drive aggressive experimental autoimmune encephalomyelitis (EAE); Tob1−/− Treg cells showed reduced regulatory function; reconstitution of Rag1−/− mice with Tob1−/− CD4+ T cells recapitulated the aggressive EAE phenotype.\",\n      \"method\": \"Tob1 KO mouse EAE model, T cell transfer into Rag1−/− mice, T cell phenotyping\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with adoptive transfer experiment, defined cellular phenotype\",\n      \"pmids\": [\"23797093\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"TOB1 associates with Smad4/5 to induce ID2 expression, which in turn restrains Th1/Th17 cell differentiation; Tob1−/− mice develop severe colitis, and Rag1−/− mice reconstituted with Tob1−/− T cells also develop severe colitis.\",\n      \"method\": \"Co-immunoprecipitation (Smad4/5), lentiviral overexpression/knockdown, RNA-seq, T cell transfer colitis model\",\n      \"journal\": \"Cellular and molecular gastroenterology and hepatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus genetic KO in vivo model; single lab\",\n      \"pmids\": [\"34920145\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Mouse Tob was cloned and shown to be ubiquitously expressed; like human Tob, mouse Tob contains proline/glutamine-rich sequences characteristic of transcription factors and has an ATTTA motif in the 3'-UTR typical of immediate-early genes, consistent with a role in response to extracellular signals.\",\n      \"method\": \"Molecular cloning, Northern blot, sequence analysis\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 — sequence/expression characterization, no direct functional mechanism established\",\n      \"pmids\": [\"9210596\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Tob1 protein is localized to P-bodies (co-immunoprecipitation and co-localization with Dcp2) in round spermatids and oocytes, consistent with a post-transcriptional regulatory role in germ cells.\",\n      \"method\": \"Immunofluorescence, co-immunoprecipitation with Dcp2, RT-ddPCR expression profiling\",\n      \"journal\": \"Cell and tissue research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — localization with Co-IP; no functional consequence demonstrated\",\n      \"pmids\": [\"26662055\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TOB1 is an anti-proliferative scaffold protein that operates through at least two interconnected mechanisms: (1) in the nucleus, it acts as a transcriptional co-repressor by binding receptor-regulated Smads (Smad1/5/8) and inhibitory Smads (Smad6/7) to suppress BMP signaling, interacting with Smad2/4 to repress IL-2 transcription, and associating with HDAC to silence the cyclin D1 promoter; and (2) in the cytoplasm, it bridges PABPC1 and the CAF1 (CNOT7/8) subunit of the CCR4-NOT deadenylase complex via its C-terminal PAM2 motifs and N-terminal BTG domain respectively, thereby recruiting deadenylase activity to polyadenylated mRNAs and accelerating their decay, including specific targets via CPEB3. Its anti-proliferative activity is negatively regulated by ERK1/2-mediated phosphorylation at Ser152/154/164 and by SCF-Skp2- and Cul4-DDB1(Cdt2)-dependent ubiquitin-proteasomal degradation, while Cdc7 phosphorylation stabilizes Tob1 to promote cell survival after mild DNA damage. Nuclear localization depends on a bipartite NLS (residues 18–40) and is opposed by an NES (residues 2–14) that is activated in ErbB2-transformed cells.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"TOB1 is an anti-proliferative scaffold protein that restrains cell growth through two interconnected mechanisms: transcriptional repression via Smad-dependent signaling and promotion of mRNA deadenylation via the CCR4-NOT complex. In the nucleus, TOB1 associates with receptor-regulated Smads (Smad1/5/8) to suppress BMP signaling and with Smad2/4 to repress IL-2 transcription, and it recruits HDAC to silence the cyclin D1 promoter, with tob-deficient mice exhibiting increased bone mass and predisposition to spontaneous tumors [PMID:11163184, PMID:11694881, PMID:12756225]. In the cytoplasm, its N-terminal BTG domain binds the CAF1 (CNOT7/CNOT8) deadenylase subunit while two C-terminal PAM2 motifs engage PABPC1, bridging the CCR4-NOT complex to polyadenylated mRNAs and accelerating their decay—an activity essential for its anti-proliferative function [PMID:17785442, PMID:19276069, PMID:23236473]. TOB1 anti-proliferative activity is negatively regulated by ERK1/2-mediated phosphorylation at Ser152/154/164 and by SCF-Skp2- and Cul4-DDB1(Cdt2)-dependent ubiquitin-proteasomal degradation, while Cdc7-mediated phosphorylation stabilizes TOB1 to promote cell survival after DNA damage [PMID:12050114, PMID:16951159, PMID:23066029].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Identification of TOB1 as an anti-proliferative protein that physically interacts with ErbB2 established the gene's foundational role as a growth suppressor regulated by receptor tyrosine kinase signaling.\",\n      \"evidence\": \"GST pulldown and co-immunoprecipitation with ErbB2, cell growth suppression assay in NIH3T3 cells\",\n      \"pmids\": [\"8632892\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of anti-proliferative action unknown\", \"Downstream targets not identified\", \"Whether ErbB2 interaction is direct or indirect in vivo unclear\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Discovery that TOB1 binds hCaf1, a deadenylase/transcription factor complex component, opened a second mechanistic axis beyond receptor tyrosine kinase interaction.\",\n      \"evidence\": \"Co-immunoprecipitation of Tob N-terminal domain with hCaf1\",\n      \"pmids\": [\"10602502\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of Caf1 interaction not demonstrated\", \"No structural detail of binding interface\", \"Role of Caf1 enzymatic activity in Tob function unknown\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Demonstration that TOB1 associates with BMP-responsive Smads and that tob-knockout mice have increased bone mass established TOB1 as a physiological negative regulator of BMP/Smad signaling in bone.\",\n      \"evidence\": \"Co-immunoprecipitation with Smad1/5/8, tob−/− knockout mouse bone phenotype, BMP2-responsive reporter assay\",\n      \"pmids\": [\"11163184\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Tob acts as a direct transcriptional corepressor at BMP-target promoters not shown\", \"Mechanism of Smad-dependent repression unclear\", \"Relationship between BMP suppression and anti-proliferative activity not delineated\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Finding that TOB1 cooperates with Smad2/4 to repress IL-2 transcription in anergic T cells extended the Smad-dependent mechanism to adaptive immunity and identified a specific target gene.\",\n      \"evidence\": \"Co-immunoprecipitation with Smad2/4, EMSA at IL-2 promoter, antisense knockdown in anergic T cells\",\n      \"pmids\": [\"11694881\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct binding of Tob to the IL-2 promoter DNA not demonstrated\", \"Post-transcriptional regulation of IL-2 not addressed\", \"Role beyond T cell anergy not examined\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Identification of ERK1/2-mediated phosphorylation at Ser152/154/164 as an inactivation mechanism resolved how mitogenic signaling overrides TOB1's growth-suppressive function, placing TOB1 in the ERK–cyclin D1–Rb pathway.\",\n      \"evidence\": \"In vitro kinase assays, Ser-to-Ala/Glu mutagenesis, tob−/− MEFs, cell cycle analysis; independently confirmed by two labs\",\n      \"pmids\": [\"12050114\", \"12151396\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether phosphorylation disrupts specific protein interactions not determined\", \"In vivo phosphorylation dynamics during cell cycle not tracked\", \"Contribution of JNK2 phosphorylation versus ERK phosphorylation not resolved\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Discovery that TOB1 recruits HDAC to repress the cyclin D1 promoter and that tob−/− mice develop spontaneous tumors established TOB1 as a bona fide tumor suppressor acting through chromatin modification.\",\n      \"evidence\": \"Tob−/− mouse tumor formation, cyclin D1 reporter assay, co-immunoprecipitation with HDAC\",\n      \"pmids\": [\"12756225\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of specific HDAC isoform(s) not resolved\", \"Whether HDAC recruitment is direct or Smad-mediated unknown\", \"Tumor spectrum and penetrance not fully characterized\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identification of TOB1 interaction with inhibitory Smads 6/7, enhancing their association with BMP type I receptors, revealed a second mode of BMP pathway suppression at the receptor level.\",\n      \"evidence\": \"Yeast two-hybrid, co-immunoprecipitation, Xenopus embryo functional assay\",\n      \"pmids\": [\"12782279\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of R-Smad versus I-Smad mechanisms not quantified\", \"Stoichiometry of Tob–Smad6 complex at the receptor unknown\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Mapping of a bipartite NLS and CRM1-dependent NES demonstrated that TOB1's anti-proliferative function requires nuclear localization and that ErbB2-driven oncogenesis antagonizes this by promoting nuclear export.\",\n      \"evidence\": \"GFP-Tob localization with NLS/NES mutagenesis, leptomycin B treatment, cell cycle assays across two independent studies\",\n      \"pmids\": [\"15235587\", \"15051490\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Signaling pathway from ErbB2 to NES activation not defined\", \"Whether cytoplasmic Tob retains deadenylation function not tested\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identification of SCF-Skp2 as the E3 ligase targeting TOB1 for proteasomal degradation explained how TOB1 protein levels are controlled during cell cycle progression.\",\n      \"evidence\": \"In vitro ubiquitination reconstitution, Skp2−/− fibroblasts showing TOB1 stabilization, Skp2 knockdown\",\n      \"pmids\": [\"16951159\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphodegron on Tob recognized by Skp2 not mapped\", \"Interplay between Skp2 and Cul4-DDB1 pathways not clarified\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstration that TOB1 simultaneously bridges PABPC1 and the CAF1-CCR4 deadenylase to enhance mRNA deadenylation in vivo unified the Caf1-binding and PABP-binding activities into a coherent recruitment model for mRNA decay.\",\n      \"evidence\": \"GST pulldown, co-immunoprecipitation, transcriptional pulse-chase mRNA decay assay, P-body co-localization\",\n      \"pmids\": [\"17785442\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific mRNA targets not identified\", \"Whether deadenylation is selective or global not determined\", \"Structural basis of simultaneous bridging not resolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Crystal structure of the TOB1 N-terminal domain bound to Caf1 revealed the atomic interface and showed that Caf1 complex formation, but not Caf1 deadenylase catalytic activity per se, is essential for growth inhibition.\",\n      \"evidence\": \"X-ray crystallography of Tob–hCaf1 complex, functional mutagenesis of interface residues\",\n      \"pmids\": [\"19276069\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full-length Tob structure (including disordered C-terminus) unavailable\", \"Whether Caf1 interaction scaffolds additional effectors beyond deadenylation not tested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"NMR analysis revealing two PAM2 motifs in the disordered C-terminus binding PABPC1, competing with eRF3, provided a thermodynamic model for translation termination-coupled deadenylation mediated by TOB1.\",\n      \"evidence\": \"NMR spectroscopy, quantitative binding affinity measurements (Kd ~20 μM)\",\n      \"pmids\": [\"20595394\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Competition with eRF3 not validated in cells\", \"Functional consequence of dual PAM2 motifs versus single motif not dissected\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Discovery that TOB1 bridges CPEB3 and Caf1 into a ternary complex for target-specific mRNA deadenylation demonstrated that TOB1 can confer substrate selectivity on the deadenylase machinery.\",\n      \"evidence\": \"Co-immunoprecipitation, GST pulldown, in vitro deadenylation reconstitution, dominant-negative mutant analysis\",\n      \"pmids\": [\"21336257\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full set of RNA-binding protein partners that confer selectivity not cataloged\", \"In vivo mRNA targets of CPEB3–Tob pathway not identified genome-wide\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Establishing that ERK phosphorylation of TOB1 does not affect its deadenylation-promoting activity revealed that TOB1 suppresses proliferation through at least two separable mechanisms: deadenylation and a phosphorylation-sensitive pathway.\",\n      \"evidence\": \"mRNA tethering functional assay, phosphomimetic mutagenesis, cell proliferation assays\",\n      \"pmids\": [\"22252318\", \"23236473\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the phosphorylation-sensitive anti-proliferative mechanism unknown\", \"Whether the two mechanisms converge on the same target mRNAs not tested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identification of Cul4-DDB1(Cdt2) as a second E3 ligase for TOB1 and Cdc7 as a stabilizing kinase after UV damage revealed a DNA damage-responsive circuit where TOB1 stabilization promotes survival.\",\n      \"evidence\": \"Ubiquitination and phosphorylation assays, tob−/− MEFs, apoptosis assays after UV irradiation\",\n      \"pmids\": [\"18850001\", \"23066029\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cdt2 degron on Tob not precisely mapped\", \"How Cdc7 phosphorylation blocks Cdt2 recognition structurally undefined\", \"Relative contribution of Skp2 versus Cdt2 pathway in different contexts unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstration that Tob1 deficiency in CD4+ T cells drives aggressive autoimmune encephalomyelitis and impairs Treg function established TOB1 as a critical checkpoint in T cell-mediated autoimmunity.\",\n      \"evidence\": \"Tob1−/− mice in EAE model, adoptive transfer of Tob1−/− CD4+ T cells into Rag1−/− recipients\",\n      \"pmids\": [\"23797093\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular targets in Tregs responsible for functional impairment not identified\", \"Whether deadenylation or Smad pathway underlies T cell phenotype unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Major unresolved questions include the genome-wide identity of mRNAs selectively targeted by TOB1-mediated deadenylation, the structural basis for full-length TOB1 function, the relative contributions of transcriptional repression versus mRNA decay in each biological context, and the mechanism by which ERK phosphorylation impairs anti-proliferative activity independently of deadenylation.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No genome-wide CLIP or similar unbiased identification of TOB1 mRNA targets\", \"No full-length TOB1 structure\", \"Phosphorylation-sensitive anti-proliferative mechanism molecularly undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [13, 16, 17, 19]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [1, 2, 7]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [8, 18, 19]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1, 9]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [13, 16]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [13, 30]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 4, 8]},\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [13, 17, 19]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [4, 7, 20]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [2, 27, 28]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [1, 8]}\n    ],\n    \"complexes\": [\n      \"CCR4-NOT\"\n    ],\n    \"partners\": [\n      \"CNOT7\",\n      \"CNOT8\",\n      \"PABPC1\",\n      \"SMAD1\",\n      \"SMAD4\",\n      \"ERBB2\",\n      \"CPEB3\",\n      \"SKP2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}