{"gene":"EIF4G3","run_date":"2026-06-09T23:54:42","timeline":{"discoveries":[{"year":1998,"finding":"Proteolysis of eIF4GII (EIF4G3) by poliovirus-induced mechanisms is required for complete shutoff of host cell protein synthesis after poliovirus infection; cleavage of eIF4GI alone is insufficient, and full shutoff coincides with cleavage of both eIF4GI and eIF4GII.","method":"Western blot analysis of eIF4GII cleavage kinetics in poliovirus-infected HeLa cells, with and without virus replication inhibitors; correlation with host protein synthesis rates","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — replicated across multiple studies (poliovirus and rhinovirus), with direct cleavage-to-function correlation; foundational mechanistic result independently confirmed","pmids":["9736694"],"is_preprint":false},{"year":1999,"finding":"Cleavage of eIF4GII (EIF4G3) by human rhinovirus 14 (HRV-14) 2A protease is the rate-limiting step in the shutoff of host cell protein synthesis after rhinovirus infection, with eIF4GII cleavage lagging behind eIF4GI cleavage.","method":"Western blot analysis of eIF4GI and eIF4GII cleavage kinetics in HRV-14-infected HeLa cells correlated with metabolic labeling of protein synthesis","journal":"Journal of virology","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct kinetic correlation between eIF4GII cleavage and translation shutoff, replicating the poliovirus findings with a distinct virus","pmids":["10074204"],"is_preprint":false},{"year":2001,"finding":"eIF4GII (EIF4G3) directly interacts with the FMDV IRES; the C-terminal fragment of eIF4GII generated by Lb protease cleavage retains IRES-binding activity. The RNA determinants for eIF4GII–IRES interaction are shared with eIF4GI.","method":"UV crosslinking and competition assays; in vitro cleavage with FMDV Lb protease followed by IRES binding assays","journal":"RNA (New York, N.Y.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding demonstrated by crosslinking and competition; single lab but multiple complementary approaches","pmids":["11565745"],"is_preprint":false},{"year":2002,"finding":"eIF4GII (EIF4G3) is NOT a substrate for HIV-1 protease in vitro, in contrast to eIF4GI which is cleaved at multiple sites by HIV-1 protease.","method":"In vitro cleavage assay using cell extracts and rabbit reticulocyte lysate system with recombinant HIV-1 protease; western blot detection","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution assay; negative result clearly documented; single lab","pmids":["12054764"],"is_preprint":false},{"year":2002,"finding":"Human rhinovirus 2 2A protease directly cleaves both eIF4GI and eIF4GII (not via activation of a cellular protease), as demonstrated using a thermosensitive 2A protease mutant.","method":"Temperature-shift experiments with thermosensitive HRV2 2A protease mutant in cytoplasmic HeLa cell extracts; western blot of cleavage products","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — mechanistic discrimination between direct and indirect cleavage using thermosensitive mutant; single lab","pmids":["12123803"],"is_preprint":false},{"year":2003,"finding":"The cleavage site of human rhinovirus 2 2A protease in eIF4GII (EIF4G3) is PLLNV(699)*GSR, located seven amino acids C-terminal to the corresponding cleavage site in eIF4GI (LSTR681*GPP), demonstrating the two isoforms have distinct cleavage sites.","method":"In vitro cleavage assay with recombinant HRV2 2Apro; N-terminal sequencing of cleavage products","journal":"Journal of virology","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct in vitro mapping of cleavage site by sequencing; replicated by multiple labs studying picornavirus-eIF4G interactions","pmids":["12663812"],"is_preprint":false},{"year":2004,"finding":"eIF4GII (EIF4G3), but not eIF4GI, is selectively recruited to capped mRNA at the onset of cell differentiation (erythropoiesis/thrombopoiesis), coincident with strong and long-lasting eIF4E phosphorylation and release of 4E-BP1 from the cap structure. Cytokines such as thrombopoietin differentially regulate eIF4GI vs. eIF4GII activities.","method":"m7GTP-Sepharose cap-affinity pulldown from differentiating cells; western blot; phosphorylation analysis","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cap-affinity pulldown demonstrating selective recruitment; single lab with multiple cell and cytokine conditions","pmids":["15143184"],"is_preprint":false},{"year":2006,"finding":"eIF4GII (EIF4G3) integrity is required for reinitiation of translation of pre-existing mRNAs after polysome run-off; de novo translation of newly synthesized mRNAs is more dependent on eIF4GI. Translation of Hsp70 mRNA is more susceptible to eIF4GII hydrolysis than to eIF4GI hydrolysis.","method":"Electroporation of IRES-driven poliovirus 2Apro mRNA in HeLa and BHK-21 cells causing differential cleavage of eIF4GI vs. eIF4GII; luciferase reporter assays; metabolic labeling","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional differentiation established by differential protease cleavage system with reporter assays; single lab","pmids":["16959778"],"is_preprint":false},{"year":2009,"finding":"FRET-based biosensors confirmed that EV 2A protease directly and specifically cleaves eIF4GII (EIF4G3) in intact infected cells, independent of other viral proteases, activated caspases, or general translation inhibition.","method":"FRET biosensors with GFP2-cleavage motif-DsRed2 fusion constructs expressed in cells; quantitative fluorescence imaging during EV infection","journal":"Biotechnology and bioengineering","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — live-cell FRET imaging with mechanistic controls; single lab","pmids":["19655339"],"is_preprint":false},{"year":2009,"finding":"Depletion of eIF4GI or eIF4GII individually only moderately inhibits cellular protein synthesis, whereas depletion of both has a slightly higher effect. VSV mRNA translation does not require eIF4GI/II, while vaccinia virus mRNA translation is substantially reduced by eIF4G depletion.","method":"siRNA depletion of eIF4GI and/or eIF4GII in HeLa cells; metabolic labeling; western blot","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown with functional translation readout; single lab","pmids":["19769989"],"is_preprint":false},{"year":2010,"finding":"EIF4G3 is required for translation of HSPA2 protein in mouse spermatocytes; loss-of-function (repro8 ENU mutation in Eif4g3) causes absence of HSPA2 protein despite presence of Hspa2 transcript, dramatically reduced CDK1 (CDC2A) kinase activity, and arrest at the G2/MI meiotic transition causing male infertility.","method":"ENU mutagenesis screen; genetic mapping; Sanger sequencing of Eif4g3 mutation; western blot for HSPA2 and CDK1 activity assay in mutant spermatocytes; RT-PCR confirming transcript presence","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic loss-of-function with specific molecular readout (HSPA2 protein absence despite mRNA presence); mechanistic link to CDK1 activity; rigorous genetic evidence","pmids":["20430745"],"is_preprint":false},{"year":2012,"finding":"DEAF1 transcriptionally regulates Eif4g3 expression in lymph node stromal cells; reduced DEAF1 function decreases eIF4GII levels and results in diminished polysomal translation of multiple genes including Anpep (aminopeptidase N).","method":"Deaf1 knockout mice and siRNA silencing; qRT-PCR; polysome profiling; western blot","journal":"Journal of molecular cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO and siRNA with polysome profiling; single lab but multiple complementary approaches","pmids":["22923498"],"is_preprint":false},{"year":2012,"finding":"CaMKI phosphorylates eIF4GII (EIF4G3) at Ser1156 in response to neuronal activity, promoting selective recruitment of eIF4GII (but not eIF4GI) to the eIF4F cap-binding complex, thereby enhancing cap-dependent translation. This mechanism regulates dendritic spine formation without affecting dendritic arborization.","method":"In vitro CaMKI phosphorylation assays; m7GTP-Sepharose pulldown from neurons treated with bicuculline/gabazine; S1156A phosphomutant; CaMKK inhibitor STO-609; RNAi knockdown of CaMKI isoforms and eIF4GII; bicistronic luciferase reporter; confocal imaging of spine density","journal":"The Journal of neuroscience : the official journal of the Society for Neuroscience","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro kinase assay identifying specific phosphorylation site, phosphomutant validation, cap-affinity pulldown, RNAi with functional readouts, multiple orthogonal methods in one study","pmids":["22514323"],"is_preprint":false},{"year":2012,"finding":"Multiple isoforms of eIF4GII (EIF4G3) are generated via alternative promoters, alternative splicing, and a non-canonical CUG initiation codon that extends the N-terminus. Novel eIF4GII isoforms rescue translation in eIF4GI/eIF4GII double-knockdown cells as effectively as eIF4GIf/e isoforms, suggesting the eIF4GII N-terminus plays a distinct role in initiation factor assembly.","method":"5' RACE, RT-PCR, reporter assays, RNAi knockdown of eIF4GI and eIF4GII followed by rescue with isoform expression constructs; metabolic labeling","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional rescue experiments with defined isoforms plus molecular characterization; single lab","pmids":["22909319"],"is_preprint":false},{"year":2013,"finding":"eIF4GII (EIF4G3) undergoes novel Cdk1-dependent N-terminal phosphorylation in nocodazole-arrested cells. Translation initiation factors including eIF4GII are enriched at microtubule organizing centers, mitotic spindle, and midbody during cytokinesis.","method":"Confocal microscopy; phosphorylation analysis by mobility shift; synchronized HeLa cells using thymidine block or Cdk1 inhibitor RO3306; metabolic labeling","journal":"Cell cycle (Georgetown, Tex.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by confocal microscopy plus biochemical phosphorylation analysis; single lab","pmids":["24091728"],"is_preprint":false},{"year":2014,"finding":"miR-520c-3p directly targets eIF4GII (EIF4G3) mRNA to negatively regulate eIF4GII protein synthesis; downregulation of eIF4GII by siRNA decreases global translation, cell proliferation, and colony formation ability, and induces cellular senescence in HeLa and DLBCL cells.","method":"miRNA overexpression, western blot, siRNA knockdown of eIF4GII, colony formation assays, xenograft mouse model, luciferase reporter (implied by direct targeting claim)","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown with multiple functional readouts; single lab with in vitro and in vivo validation","pmids":["24497838"],"is_preprint":false},{"year":2018,"finding":"EIF4G3 localizes to the nucleus of mouse spermatocytes and is highly enriched in the XY body (the transcriptionally inactive sex chromosome domain); many translation-related proteins also localize to the XY body, suggesting a role in mRNA metabolism or poising of translation complexes before meiotic divisions.","method":"Immunofluorescence confocal microscopy and fractionation during spermatogenesis; co-localization with XY body markers","journal":"Biology of reproduction","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by immunofluorescence with multiple markers; single lab; functional consequence inferred but not directly tested","pmids":["29161344"],"is_preprint":false},{"year":2001,"finding":"Both eIF4GI and eIF4GII are cleaved in Jurkat T cells treated with proteasome inhibitors (MG132, lactacystin) or immunosuppressants (FTY720, cyclosporin A) via caspase-8-independent mechanisms. Novel eIF4GI cleavage fragments generated lack the ability to interact with eIF4E.","method":"Western blot with specific anti-peptide antisera against eIF4GI and eIF4GII in wild-type and caspase-8-deficient Jurkat cells; caspase activity assays","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — use of caspase-8-deficient cell line as mechanistic control; single lab","pmids":["11513883"],"is_preprint":false}],"current_model":"EIF4G3 (eIF4GII) is a scaffold protein component of the eIF4F translation initiation complex that bridges the mRNA 5' cap (via eIF4E) and the ribosome (via eIF3); it is selectively cleaved by picornavirus 2A proteases at a distinct site from eIF4GI, and cleavage of both isoforms is required for complete shutoff of host protein synthesis during viral infection; in mammalian cells, EIF4G3 has non-redundant functions from eIF4GI including selective recruitment to capped mRNA during cell differentiation, CaMKI-mediated phosphorylation at Ser1156 to enhance cap-dependent neuronal translation and spine formation, Cdk1-dependent phosphorylation during mitosis, nuclear localization in the XY body of spermatocytes, and a specific requirement for translating HSPA2 in spermatocytes to enable CDK1 activation and meiotic exit."},"narrative":{"mechanistic_narrative":"EIF4G3 (eIF4GII) is a scaffold subunit of the eIF4F cap-binding complex that supports cap-dependent translation initiation through selective, regulated recruitment to capped mRNA, functioning non-redundantly with its paralog eIF4GI [PMID:15143184, PMID:22514323]. During cell differentiation it is preferentially recruited to the m7G cap, coincident with sustained eIF4E phosphorylation and 4E-BP1 release, indicating context-specific deployment of EIF4G3 versus eIF4GI [PMID:15143184]. Its participation in the cap complex is gated by phosphorylation: CaMKI phosphorylates EIF4G3 at Ser1156 in response to neuronal activity to selectively promote its assembly into eIF4F and enhance cap-dependent translation driving dendritic spine formation [PMID:22514323], and it undergoes Cdk1-dependent N-terminal phosphorylation during mitosis when translation factors concentrate at the spindle, microtubule organizing centers, and midbody [PMID:24091728]. In male meiosis EIF4G3 is required to translate HSPA2 mRNA, and its loss abolishes HSPA2 protein while sparing transcript, collapsing CDK1 kinase activity and arresting spermatocytes at the G2/MI transition [PMID:20430745]; EIF4G3 also localizes to the spermatocyte nucleus and is enriched in the transcriptionally silent XY body [PMID:29161344]. As a translation-initiation hub, EIF4G3 is a target of picornaviral 2A/Lb proteases, which cleave it at a site distinct from eIF4GI (PLLNV699*GSR), and cleavage of both isoforms is required for complete host translational shutoff during infection [PMID:9736694, PMID:12663812]. EIF4G3 abundance is controlled both transcriptionally by DEAF1 and post-transcriptionally by miR-520c-3p, the latter limiting global translation and proliferation [PMID:22923498, PMID:24497838].","teleology":[{"year":1998,"claim":"Established that EIF4G3, distinct from eIF4GI, must be proteolyzed for complete host translation shutoff, identifying it as a functionally relevant target during picornaviral infection rather than a redundant paralog.","evidence":"Western blot of eIF4GII cleavage kinetics in poliovirus-infected HeLa cells correlated with protein synthesis rates","pmids":["9736694"],"confidence":"High","gaps":["Did not map the cleavage site or the responsible protease","Did not determine whether the cleavage fragments retain partial function"]},{"year":1999,"claim":"Showed that EIF4G3 cleavage is the rate-limiting step in rhinovirus-induced shutoff, refining the kinetic hierarchy by which the two eIF4G isoforms are inactivated.","evidence":"Western blot of eIF4GI/eIF4GII cleavage kinetics in HRV-14-infected HeLa cells with metabolic labeling","pmids":["10074204"],"confidence":"High","gaps":["Mechanism explaining slower eIF4GII cleavage not defined"]},{"year":2001,"claim":"Determined that EIF4G3 directly binds the FMDV IRES and that the protease-generated C-terminal fragment retains IRES binding, defining how the cleaved factor can still support viral cap-independent translation.","evidence":"UV crosslinking, competition assays, and in vitro Lb protease cleavage followed by IRES binding","pmids":["11565745"],"confidence":"Medium","gaps":["Single lab","RNA determinants shared with eIF4GI, so isoform-specific contribution unresolved"]},{"year":2002,"claim":"Distinguished EIF4G3 protease susceptibility profiles by showing it is not cleaved by HIV-1 protease while eIF4GI is, and that rhinovirus 2A cleaves it directly rather than via a cellular protease.","evidence":"In vitro cleavage assays with recombinant HIV-1 protease and a thermosensitive HRV2 2A mutant","pmids":["12054764","12123803"],"confidence":"Medium","gaps":["In vitro systems only","Single lab per result"]},{"year":2003,"claim":"Mapped the rhinovirus 2A cleavage site in EIF4G3 to PLLNV699*GSR, seven residues C-terminal to the eIF4GI site, proving the isoforms are processed at non-identical positions.","evidence":"In vitro cleavage with recombinant HRV2 2Apro and N-terminal sequencing of products","pmids":["12663812"],"confidence":"High","gaps":["Functional consequence of the distinct cut site for translation not addressed here"]},{"year":2004,"claim":"Revealed EIF4G3-specific, non-redundant translational roles by showing selective recruitment to capped mRNA at the onset of differentiation, linking it to eIF4E phosphorylation and cytokine signaling.","evidence":"m7GTP-Sepharose cap-affinity pulldown from differentiating erythroid/megakaryocytic cells with phosphorylation analysis","pmids":["15143184"],"confidence":"Medium","gaps":["mRNA targets selectively translated via EIF4G3 not identified","Single lab"]},{"year":2006,"claim":"Functionally separated EIF4G3 from eIF4GI by showing it is preferentially required for reinitiation on pre-existing mRNAs and for Hsp70 mRNA translation, defining distinct mRNA-class dependencies.","evidence":"Differential 2Apro-mediated cleavage of eIF4GI vs eIF4GII with luciferase reporters and metabolic labeling","pmids":["16959778"],"confidence":"Medium","gaps":["Molecular basis for mRNA selectivity unresolved","Single lab"]},{"year":2009,"claim":"Quantified the cellular requirement for EIF4G3 in bulk translation by RNAi and confirmed direct, specific 2A cleavage in living infected cells, bounding its individual contribution and virus-dependence.","evidence":"siRNA depletion with metabolic labeling, and FRET cleavage biosensors during enterovirus infection","pmids":["19769989","19655339"],"confidence":"Medium","gaps":["Partial functional redundancy with eIF4GI limits interpretation of single knockdown","Single lab per study"]},{"year":2010,"claim":"Defined an essential in vivo function: EIF4G3 is specifically required to translate HSPA2 in spermatocytes, linking its loss to failed CDK1 activation and meiotic arrest.","evidence":"ENU repro8 mutant mice with western blot for HSPA2/CDK1 activity and RT-PCR confirming transcript presence","pmids":["20430745"],"confidence":"High","gaps":["How EIF4G3 selectively engages Hspa2 mRNA not defined","Other meiotic mRNA targets not identified"]},{"year":2012,"claim":"Identified phosphoregulation of EIF4G3 by CaMKI at Ser1156 as an activity-dependent switch promoting its selective entry into eIF4F to drive spine formation, establishing a signaling-to-translation mechanism unique to this isoform.","evidence":"In vitro kinase assays, S1156A phosphomutant, cap-affinity pulldown, RNAi, and spine-density imaging in neurons","pmids":["22514323"],"confidence":"High","gaps":["Specific mRNAs translated downstream not enumerated","Structural basis of phospho-dependent recruitment unknown"]},{"year":2012,"claim":"Showed EIF4G3 expression and isoform diversity are actively controlled — transcriptionally by DEAF1 and via alternative promoters/splicing/CUG initiation — with the EIF4G3 N-terminus contributing distinctly to initiation-factor assembly.","evidence":"Deaf1 KO/siRNA with polysome profiling; 5'RACE, RT-PCR and rescue of double-knockdown cells with defined isoforms","pmids":["22923498","22909319"],"confidence":"Medium","gaps":["Functional role of N-terminal extension mechanistically undefined","Single lab per study"]},{"year":2013,"claim":"Connected EIF4G3 to the cell cycle by identifying Cdk1-dependent N-terminal phosphorylation in mitosis and its localization to spindle, MTOC, and midbody, implying spatially regulated translation during division.","evidence":"Confocal microscopy and mobility-shift phosphorylation analysis in synchronized HeLa cells with Cdk1 inhibitor","pmids":["24091728"],"confidence":"Medium","gaps":["Functional consequence of mitotic phosphorylation not tested","Single lab"]},{"year":2014,"claim":"Demonstrated post-transcriptional control of EIF4G3 by miR-520c-3p, linking its abundance to global translation, proliferation, and senescence in cancer cells.","evidence":"miRNA overexpression, siRNA knockdown, colony-formation and xenograft assays","pmids":["24497838"],"confidence":"Medium","gaps":["Direct luciferase target validation only implied","Single lab"]},{"year":2018,"claim":"Localized EIF4G3 to the spermatocyte nucleus and the transcriptionally silent XY body, raising the possibility of pre-positioning translation complexes ahead of meiotic divisions.","evidence":"Immunofluorescence confocal microscopy and fractionation during spermatogenesis with XY body markers","pmids":["29161344"],"confidence":"Medium","gaps":["Functional role at the XY body inferred but not tested","Single lab"]},{"year":null,"claim":"The transcriptome-wide set of mRNAs selectively dependent on EIF4G3 versus eIF4GI, and the structural basis by which phosphorylation and isoform N-termini gate its entry into eIF4F, remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No genome-wide EIF4G3-specific translatome","No structural model of phospho-regulated eIF4F assembly","Mechanism of mRNA selectivity (Hspa2, reinitiation substrates) unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[6,12]},{"term_id":"GO:0045182","term_label":"translation regulator activity","supporting_discovery_ids":[6,7,12]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[2]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[16]},{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[14]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[6,12]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[6,12,10]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[0,5]},{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[10,16]}],"complexes":["eIF4F"],"partners":["EIF4E","HSPA2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O43432","full_name":"Eukaryotic translation initiation factor 4 gamma 3","aliases":["eIF-4-gamma II","eIF4GII"],"length_aa":1585,"mass_kda":176.7,"function":"Component of the protein complex eIF4F, which is involved in the recognition of the mRNA cap, ATP-dependent unwinding of 5'-terminal secondary structure and recruitment of mRNA to the ribosome (PubMed:9418880). Functional homolog of EIF4G1 (PubMed:9418880)","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/O43432/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/EIF4G3","classification":"Not Classified","n_dependent_lines":4,"n_total_lines":1208,"dependency_fraction":0.0033112582781456954},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"DDX6","stoichiometry":0.2},{"gene":"EIF2S3","stoichiometry":0.2},{"gene":"EIF3B","stoichiometry":0.2},{"gene":"EIF4A1","stoichiometry":0.2},{"gene":"GPAT3","stoichiometry":0.2},{"gene":"GSPT1","stoichiometry":0.2},{"gene":"PSMC4","stoichiometry":0.2},{"gene":"PSPC1","stoichiometry":0.2},{"gene":"VRK2","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/EIF4G3","total_profiled":1310},"omim":[{"mim_id":"615908","title":"MICRO RNA 520C; MIR520C","url":"https://www.omim.org/entry/615908"},{"mim_id":"615828","title":"VULTO-VAN SILFHOUT-DE VRIES SYNDROME; VSVS","url":"https://www.omim.org/entry/615828"},{"mim_id":"604662","title":"POTASSIUM CHANNEL-INTERACTING PROTEIN 3; KCNIP3","url":"https://www.omim.org/entry/604662"},{"mim_id":"603929","title":"EUKARYOTIC TRANSLATION INITIATION FACTOR 4-GAMMA, 3; EIF4G3","url":"https://www.omim.org/entry/603929"},{"mim_id":"602635","title":"DEAF1 TRANSCRIPTION FACTOR; DEAF1","url":"https://www.omim.org/entry/602635"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/EIF4G3"},"hgnc":{"alias_symbol":["eIF4GII"],"prev_symbol":[]},"alphafold":{"accession":"O43432","domains":[{"cath_id":"1.25.40.180","chopping":"751-985","consensus_level":"medium","plddt":81.8028,"start":751,"end":985},{"cath_id":"1.25.40.180","chopping":"1220-1407","consensus_level":"medium","plddt":87.0397,"start":1220,"end":1407},{"cath_id":"1.25.40.180","chopping":"1425-1585","consensus_level":"medium","plddt":84.4242,"start":1425,"end":1585}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O43432","model_url":"https://alphafold.ebi.ac.uk/files/AF-O43432-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O43432-F1-predicted_aligned_error_v6.png","plddt_mean":55.34},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=EIF4G3","jax_strain_url":"https://www.jax.org/strain/search?query=EIF4G3"},"sequence":{"accession":"O43432","fasta_url":"https://rest.uniprot.org/uniprotkb/O43432.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O43432/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O43432"}},"corpus_meta":[{"pmid":"9736694","id":"PMC_9736694","title":"Proteolysis of human eukaryotic translation initiation factor eIF4GII, but not eIF4GI, coincides with the shutoff of host protein synthesis after poliovirus infection.","date":"1998","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/9736694","citation_count":287,"is_preprint":false},{"pmid":"11565745","id":"PMC_11565745","title":"IRES interaction with translation initiation factors: functional characterization of novel RNA contacts with eIF3, eIF4B, and eIF4GII.","date":"2001","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/11565745","citation_count":103,"is_preprint":false},{"pmid":"10074204","id":"PMC_10074204","title":"Eukaryotic initiation factor 4GII (eIF4GII), but not eIF4GI, cleavage correlates with inhibition of host cell protein synthesis after human rhinovirus infection.","date":"1999","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/10074204","citation_count":102,"is_preprint":false},{"pmid":"35780119","id":"PMC_35780119","title":"Circular RNA EIF4G3 suppresses gastric cancer progression through inhibition of β-catenin by promoting δ-catenin ubiquitin degradation and upregulating SIK1.","date":"2022","source":"Molecular cancer","url":"https://pubmed.ncbi.nlm.nih.gov/35780119","citation_count":65,"is_preprint":false},{"pmid":"20430745","id":"PMC_20430745","title":"Mutation of Eif4g3, encoding a eukaryotic translation initiation factor, causes male infertility and meiotic arrest of mouse spermatocytes.","date":"2010","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/20430745","citation_count":64,"is_preprint":false},{"pmid":"12054764","id":"PMC_12054764","title":"In vitro cleavage of eIF4GI but not eIF4GII by HIV-1 protease and its effects on translation in the rabbit reticulocyte lysate system.","date":"2002","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/12054764","citation_count":64,"is_preprint":false},{"pmid":"24091728","id":"PMC_24091728","title":"Phosphorylation of eIF4GII and 4E-BP1 in response to nocodazole treatment: a reappraisal of translation initiation during mitosis.","date":"2013","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/24091728","citation_count":45,"is_preprint":false},{"pmid":"16959778","id":"PMC_16959778","title":"Differential cleavage of eIF4GI and eIF4GII in mammalian cells. Effects on translation.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16959778","citation_count":39,"is_preprint":false},{"pmid":"24497838","id":"PMC_24497838","title":"Down-regulation of eIF4GII by miR-520c-3p represses diffuse large B cell lymphoma development.","date":"2014","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24497838","citation_count":36,"is_preprint":false},{"pmid":"15143184","id":"PMC_15143184","title":"Selective modification of eukaryotic initiation factor 4F (eIF4F) at the onset of cell differentiation: recruitment of eIF4GII and long-lasting phosphorylation of eIF4E.","date":"2004","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/15143184","citation_count":36,"is_preprint":false},{"pmid":"22923498","id":"PMC_22923498","title":"Reduced DEAF1 function during type 1 diabetes inhibits translation in lymph node stromal cells by suppressing Eif4g3.","date":"2012","source":"Journal of molecular cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/22923498","citation_count":35,"is_preprint":false},{"pmid":"19769989","id":"PMC_19769989","title":"Translation of mRNAs from vesicular stomatitis virus and vaccinia virus is differentially blocked in cells with depletion of eIF4GI and/or eIF4GII.","date":"2009","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/19769989","citation_count":27,"is_preprint":false},{"pmid":"12663812","id":"PMC_12663812","title":"Human rhinovirus 2A proteinase cleavage sites in eukaryotic initiation factors (eIF) 4GI and eIF4GII are different.","date":"2003","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/12663812","citation_count":25,"is_preprint":false},{"pmid":"29161344","id":"PMC_29161344","title":"Nuclear localization of EIF4G3 suggests a role for the XY body in translational regulation during spermatogenesis in mice.","date":"2018","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/29161344","citation_count":24,"is_preprint":false},{"pmid":"22514323","id":"PMC_22514323","title":"Regulation of neuronal mRNA translation by CaM-kinase I phosphorylation of eIF4GII.","date":"2012","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/22514323","citation_count":21,"is_preprint":false},{"pmid":"22909319","id":"PMC_22909319","title":"Multiple isoforms of the translation initiation factor eIF4GII are generated via use of alternative promoters, splice sites and a non-canonical initiation codon.","date":"2012","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/22909319","citation_count":16,"is_preprint":false},{"pmid":"12123803","id":"PMC_12123803","title":"A thermosensitive mutant of HRV2 2A proteinase: evidence for direct cleavage of eIF4GI and eIF4GII.","date":"2002","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/12123803","citation_count":15,"is_preprint":false},{"pmid":"19655339","id":"PMC_19655339","title":"Visualizing and quantifying the differential cleavages of the eukaryotic translation initiation factors eIF4GI and eIF4GII in the enterovirus-infected cell.","date":"2009","source":"Biotechnology and bioengineering","url":"https://pubmed.ncbi.nlm.nih.gov/19655339","citation_count":14,"is_preprint":false},{"pmid":"34194495","id":"PMC_34194495","title":"Chidamide and Radiotherapy Synergistically Induce Cell Apoptosis and Suppress Tumor Growth and Cancer Stemness by Regulating the MiR-375-EIF4G3 Axis in Lung Squamous Cell Carcinomas.","date":"2021","source":"Journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/34194495","citation_count":13,"is_preprint":false},{"pmid":"31257089","id":"PMC_31257089","title":"Circ-EIF4G3 promotes the development of gastric cancer by sponging miR-335.","date":"2019","source":"Pathology, research and practice","url":"https://pubmed.ncbi.nlm.nih.gov/31257089","citation_count":12,"is_preprint":false},{"pmid":"11513883","id":"PMC_11513883","title":"Proteasome inhibitors and immunosuppressive drugs promote the cleavage of eIF4GI and eIF4GII by caspase-8-independent mechanisms in Jurkat T cell lines.","date":"2001","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/11513883","citation_count":9,"is_preprint":false},{"pmid":"41776682","id":"PMC_41776682","title":"The related EIF4G3 and EIF4G4 initiation factors from Leishmania: dissimilar modes of action during translation revealed by a comparative proteomic approach.","date":"2026","source":"Parasites & vectors","url":"https://pubmed.ncbi.nlm.nih.gov/41776682","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":12897,"output_tokens":4471,"usd":0.052878,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12448,"output_tokens":4363,"usd":0.085657,"stage2_stop_reason":"end_turn"},"total_usd":0.138535,"stage1_batch_id":"msgbatch_01AsR7g8dGTEiEw9U83bJeWn","stage2_batch_id":"msgbatch_01YV5ZyxtFNUZEjxRcpd9jzb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1998,\n      \"finding\": \"Proteolysis of eIF4GII (EIF4G3) by poliovirus-induced mechanisms is required for complete shutoff of host cell protein synthesis after poliovirus infection; cleavage of eIF4GI alone is insufficient, and full shutoff coincides with cleavage of both eIF4GI and eIF4GII.\",\n      \"method\": \"Western blot analysis of eIF4GII cleavage kinetics in poliovirus-infected HeLa cells, with and without virus replication inhibitors; correlation with host protein synthesis rates\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — replicated across multiple studies (poliovirus and rhinovirus), with direct cleavage-to-function correlation; foundational mechanistic result independently confirmed\",\n      \"pmids\": [\"9736694\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Cleavage of eIF4GII (EIF4G3) by human rhinovirus 14 (HRV-14) 2A protease is the rate-limiting step in the shutoff of host cell protein synthesis after rhinovirus infection, with eIF4GII cleavage lagging behind eIF4GI cleavage.\",\n      \"method\": \"Western blot analysis of eIF4GI and eIF4GII cleavage kinetics in HRV-14-infected HeLa cells correlated with metabolic labeling of protein synthesis\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct kinetic correlation between eIF4GII cleavage and translation shutoff, replicating the poliovirus findings with a distinct virus\",\n      \"pmids\": [\"10074204\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"eIF4GII (EIF4G3) directly interacts with the FMDV IRES; the C-terminal fragment of eIF4GII generated by Lb protease cleavage retains IRES-binding activity. The RNA determinants for eIF4GII–IRES interaction are shared with eIF4GI.\",\n      \"method\": \"UV crosslinking and competition assays; in vitro cleavage with FMDV Lb protease followed by IRES binding assays\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding demonstrated by crosslinking and competition; single lab but multiple complementary approaches\",\n      \"pmids\": [\"11565745\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"eIF4GII (EIF4G3) is NOT a substrate for HIV-1 protease in vitro, in contrast to eIF4GI which is cleaved at multiple sites by HIV-1 protease.\",\n      \"method\": \"In vitro cleavage assay using cell extracts and rabbit reticulocyte lysate system with recombinant HIV-1 protease; western blot detection\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution assay; negative result clearly documented; single lab\",\n      \"pmids\": [\"12054764\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Human rhinovirus 2 2A protease directly cleaves both eIF4GI and eIF4GII (not via activation of a cellular protease), as demonstrated using a thermosensitive 2A protease mutant.\",\n      \"method\": \"Temperature-shift experiments with thermosensitive HRV2 2A protease mutant in cytoplasmic HeLa cell extracts; western blot of cleavage products\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mechanistic discrimination between direct and indirect cleavage using thermosensitive mutant; single lab\",\n      \"pmids\": [\"12123803\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The cleavage site of human rhinovirus 2 2A protease in eIF4GII (EIF4G3) is PLLNV(699)*GSR, located seven amino acids C-terminal to the corresponding cleavage site in eIF4GI (LSTR681*GPP), demonstrating the two isoforms have distinct cleavage sites.\",\n      \"method\": \"In vitro cleavage assay with recombinant HRV2 2Apro; N-terminal sequencing of cleavage products\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct in vitro mapping of cleavage site by sequencing; replicated by multiple labs studying picornavirus-eIF4G interactions\",\n      \"pmids\": [\"12663812\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"eIF4GII (EIF4G3), but not eIF4GI, is selectively recruited to capped mRNA at the onset of cell differentiation (erythropoiesis/thrombopoiesis), coincident with strong and long-lasting eIF4E phosphorylation and release of 4E-BP1 from the cap structure. Cytokines such as thrombopoietin differentially regulate eIF4GI vs. eIF4GII activities.\",\n      \"method\": \"m7GTP-Sepharose cap-affinity pulldown from differentiating cells; western blot; phosphorylation analysis\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cap-affinity pulldown demonstrating selective recruitment; single lab with multiple cell and cytokine conditions\",\n      \"pmids\": [\"15143184\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"eIF4GII (EIF4G3) integrity is required for reinitiation of translation of pre-existing mRNAs after polysome run-off; de novo translation of newly synthesized mRNAs is more dependent on eIF4GI. Translation of Hsp70 mRNA is more susceptible to eIF4GII hydrolysis than to eIF4GI hydrolysis.\",\n      \"method\": \"Electroporation of IRES-driven poliovirus 2Apro mRNA in HeLa and BHK-21 cells causing differential cleavage of eIF4GI vs. eIF4GII; luciferase reporter assays; metabolic labeling\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional differentiation established by differential protease cleavage system with reporter assays; single lab\",\n      \"pmids\": [\"16959778\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"FRET-based biosensors confirmed that EV 2A protease directly and specifically cleaves eIF4GII (EIF4G3) in intact infected cells, independent of other viral proteases, activated caspases, or general translation inhibition.\",\n      \"method\": \"FRET biosensors with GFP2-cleavage motif-DsRed2 fusion constructs expressed in cells; quantitative fluorescence imaging during EV infection\",\n      \"journal\": \"Biotechnology and bioengineering\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — live-cell FRET imaging with mechanistic controls; single lab\",\n      \"pmids\": [\"19655339\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Depletion of eIF4GI or eIF4GII individually only moderately inhibits cellular protein synthesis, whereas depletion of both has a slightly higher effect. VSV mRNA translation does not require eIF4GI/II, while vaccinia virus mRNA translation is substantially reduced by eIF4G depletion.\",\n      \"method\": \"siRNA depletion of eIF4GI and/or eIF4GII in HeLa cells; metabolic labeling; western blot\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown with functional translation readout; single lab\",\n      \"pmids\": [\"19769989\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"EIF4G3 is required for translation of HSPA2 protein in mouse spermatocytes; loss-of-function (repro8 ENU mutation in Eif4g3) causes absence of HSPA2 protein despite presence of Hspa2 transcript, dramatically reduced CDK1 (CDC2A) kinase activity, and arrest at the G2/MI meiotic transition causing male infertility.\",\n      \"method\": \"ENU mutagenesis screen; genetic mapping; Sanger sequencing of Eif4g3 mutation; western blot for HSPA2 and CDK1 activity assay in mutant spermatocytes; RT-PCR confirming transcript presence\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic loss-of-function with specific molecular readout (HSPA2 protein absence despite mRNA presence); mechanistic link to CDK1 activity; rigorous genetic evidence\",\n      \"pmids\": [\"20430745\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"DEAF1 transcriptionally regulates Eif4g3 expression in lymph node stromal cells; reduced DEAF1 function decreases eIF4GII levels and results in diminished polysomal translation of multiple genes including Anpep (aminopeptidase N).\",\n      \"method\": \"Deaf1 knockout mice and siRNA silencing; qRT-PCR; polysome profiling; western blot\",\n      \"journal\": \"Journal of molecular cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO and siRNA with polysome profiling; single lab but multiple complementary approaches\",\n      \"pmids\": [\"22923498\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"CaMKI phosphorylates eIF4GII (EIF4G3) at Ser1156 in response to neuronal activity, promoting selective recruitment of eIF4GII (but not eIF4GI) to the eIF4F cap-binding complex, thereby enhancing cap-dependent translation. This mechanism regulates dendritic spine formation without affecting dendritic arborization.\",\n      \"method\": \"In vitro CaMKI phosphorylation assays; m7GTP-Sepharose pulldown from neurons treated with bicuculline/gabazine; S1156A phosphomutant; CaMKK inhibitor STO-609; RNAi knockdown of CaMKI isoforms and eIF4GII; bicistronic luciferase reporter; confocal imaging of spine density\",\n      \"journal\": \"The Journal of neuroscience : the official journal of the Society for Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro kinase assay identifying specific phosphorylation site, phosphomutant validation, cap-affinity pulldown, RNAi with functional readouts, multiple orthogonal methods in one study\",\n      \"pmids\": [\"22514323\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Multiple isoforms of eIF4GII (EIF4G3) are generated via alternative promoters, alternative splicing, and a non-canonical CUG initiation codon that extends the N-terminus. Novel eIF4GII isoforms rescue translation in eIF4GI/eIF4GII double-knockdown cells as effectively as eIF4GIf/e isoforms, suggesting the eIF4GII N-terminus plays a distinct role in initiation factor assembly.\",\n      \"method\": \"5' RACE, RT-PCR, reporter assays, RNAi knockdown of eIF4GI and eIF4GII followed by rescue with isoform expression constructs; metabolic labeling\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional rescue experiments with defined isoforms plus molecular characterization; single lab\",\n      \"pmids\": [\"22909319\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"eIF4GII (EIF4G3) undergoes novel Cdk1-dependent N-terminal phosphorylation in nocodazole-arrested cells. Translation initiation factors including eIF4GII are enriched at microtubule organizing centers, mitotic spindle, and midbody during cytokinesis.\",\n      \"method\": \"Confocal microscopy; phosphorylation analysis by mobility shift; synchronized HeLa cells using thymidine block or Cdk1 inhibitor RO3306; metabolic labeling\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by confocal microscopy plus biochemical phosphorylation analysis; single lab\",\n      \"pmids\": [\"24091728\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"miR-520c-3p directly targets eIF4GII (EIF4G3) mRNA to negatively regulate eIF4GII protein synthesis; downregulation of eIF4GII by siRNA decreases global translation, cell proliferation, and colony formation ability, and induces cellular senescence in HeLa and DLBCL cells.\",\n      \"method\": \"miRNA overexpression, western blot, siRNA knockdown of eIF4GII, colony formation assays, xenograft mouse model, luciferase reporter (implied by direct targeting claim)\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown with multiple functional readouts; single lab with in vitro and in vivo validation\",\n      \"pmids\": [\"24497838\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"EIF4G3 localizes to the nucleus of mouse spermatocytes and is highly enriched in the XY body (the transcriptionally inactive sex chromosome domain); many translation-related proteins also localize to the XY body, suggesting a role in mRNA metabolism or poising of translation complexes before meiotic divisions.\",\n      \"method\": \"Immunofluorescence confocal microscopy and fractionation during spermatogenesis; co-localization with XY body markers\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by immunofluorescence with multiple markers; single lab; functional consequence inferred but not directly tested\",\n      \"pmids\": [\"29161344\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Both eIF4GI and eIF4GII are cleaved in Jurkat T cells treated with proteasome inhibitors (MG132, lactacystin) or immunosuppressants (FTY720, cyclosporin A) via caspase-8-independent mechanisms. Novel eIF4GI cleavage fragments generated lack the ability to interact with eIF4E.\",\n      \"method\": \"Western blot with specific anti-peptide antisera against eIF4GI and eIF4GII in wild-type and caspase-8-deficient Jurkat cells; caspase activity assays\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — use of caspase-8-deficient cell line as mechanistic control; single lab\",\n      \"pmids\": [\"11513883\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"EIF4G3 (eIF4GII) is a scaffold protein component of the eIF4F translation initiation complex that bridges the mRNA 5' cap (via eIF4E) and the ribosome (via eIF3); it is selectively cleaved by picornavirus 2A proteases at a distinct site from eIF4GI, and cleavage of both isoforms is required for complete shutoff of host protein synthesis during viral infection; in mammalian cells, EIF4G3 has non-redundant functions from eIF4GI including selective recruitment to capped mRNA during cell differentiation, CaMKI-mediated phosphorylation at Ser1156 to enhance cap-dependent neuronal translation and spine formation, Cdk1-dependent phosphorylation during mitosis, nuclear localization in the XY body of spermatocytes, and a specific requirement for translating HSPA2 in spermatocytes to enable CDK1 activation and meiotic exit.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"EIF4G3 (eIF4GII) is a scaffold subunit of the eIF4F cap-binding complex that supports cap-dependent translation initiation through selective, regulated recruitment to capped mRNA, functioning non-redundantly with its paralog eIF4GI [#6, #12]. During cell differentiation it is preferentially recruited to the m7G cap, coincident with sustained eIF4E phosphorylation and 4E-BP1 release, indicating context-specific deployment of EIF4G3 versus eIF4GI [#6]. Its participation in the cap complex is gated by phosphorylation: CaMKI phosphorylates EIF4G3 at Ser1156 in response to neuronal activity to selectively promote its assembly into eIF4F and enhance cap-dependent translation driving dendritic spine formation [#12], and it undergoes Cdk1-dependent N-terminal phosphorylation during mitosis when translation factors concentrate at the spindle, microtubule organizing centers, and midbody [#14]. In male meiosis EIF4G3 is required to translate HSPA2 mRNA, and its loss abolishes HSPA2 protein while sparing transcript, collapsing CDK1 kinase activity and arresting spermatocytes at the G2/MI transition [#10]; EIF4G3 also localizes to the spermatocyte nucleus and is enriched in the transcriptionally silent XY body [#16]. As a translation-initiation hub, EIF4G3 is a target of picornaviral 2A/Lb proteases, which cleave it at a site distinct from eIF4GI (PLLNV699*GSR), and cleavage of both isoforms is required for complete host translational shutoff during infection [#0, #5]. EIF4G3 abundance is controlled both transcriptionally by DEAF1 and post-transcriptionally by miR-520c-3p, the latter limiting global translation and proliferation [#11, #15].\"\n  ,\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Established that EIF4G3, distinct from eIF4GI, must be proteolyzed for complete host translation shutoff, identifying it as a functionally relevant target during picornaviral infection rather than a redundant paralog.\",\n      \"evidence\": \"Western blot of eIF4GII cleavage kinetics in poliovirus-infected HeLa cells correlated with protein synthesis rates\",\n      \"pmids\": [\"9736694\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not map the cleavage site or the responsible protease\", \"Did not determine whether the cleavage fragments retain partial function\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Showed that EIF4G3 cleavage is the rate-limiting step in rhinovirus-induced shutoff, refining the kinetic hierarchy by which the two eIF4G isoforms are inactivated.\",\n      \"evidence\": \"Western blot of eIF4GI/eIF4GII cleavage kinetics in HRV-14-infected HeLa cells with metabolic labeling\",\n      \"pmids\": [\"10074204\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism explaining slower eIF4GII cleavage not defined\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Determined that EIF4G3 directly binds the FMDV IRES and that the protease-generated C-terminal fragment retains IRES binding, defining how the cleaved factor can still support viral cap-independent translation.\",\n      \"evidence\": \"UV crosslinking, competition assays, and in vitro Lb protease cleavage followed by IRES binding\",\n      \"pmids\": [\"11565745\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"RNA determinants shared with eIF4GI, so isoform-specific contribution unresolved\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Distinguished EIF4G3 protease susceptibility profiles by showing it is not cleaved by HIV-1 protease while eIF4GI is, and that rhinovirus 2A cleaves it directly rather than via a cellular protease.\",\n      \"evidence\": \"In vitro cleavage assays with recombinant HIV-1 protease and a thermosensitive HRV2 2A mutant\",\n      \"pmids\": [\"12054764\", \"12123803\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vitro systems only\", \"Single lab per result\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Mapped the rhinovirus 2A cleavage site in EIF4G3 to PLLNV699*GSR, seven residues C-terminal to the eIF4GI site, proving the isoforms are processed at non-identical positions.\",\n      \"evidence\": \"In vitro cleavage with recombinant HRV2 2Apro and N-terminal sequencing of products\",\n      \"pmids\": [\"12663812\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of the distinct cut site for translation not addressed here\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Revealed EIF4G3-specific, non-redundant translational roles by showing selective recruitment to capped mRNA at the onset of differentiation, linking it to eIF4E phosphorylation and cytokine signaling.\",\n      \"evidence\": \"m7GTP-Sepharose cap-affinity pulldown from differentiating erythroid/megakaryocytic cells with phosphorylation analysis\",\n      \"pmids\": [\"15143184\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"mRNA targets selectively translated via EIF4G3 not identified\", \"Single lab\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Functionally separated EIF4G3 from eIF4GI by showing it is preferentially required for reinitiation on pre-existing mRNAs and for Hsp70 mRNA translation, defining distinct mRNA-class dependencies.\",\n      \"evidence\": \"Differential 2Apro-mediated cleavage of eIF4GI vs eIF4GII with luciferase reporters and metabolic labeling\",\n      \"pmids\": [\"16959778\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis for mRNA selectivity unresolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Quantified the cellular requirement for EIF4G3 in bulk translation by RNAi and confirmed direct, specific 2A cleavage in living infected cells, bounding its individual contribution and virus-dependence.\",\n      \"evidence\": \"siRNA depletion with metabolic labeling, and FRET cleavage biosensors during enterovirus infection\",\n      \"pmids\": [\"19769989\", \"19655339\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Partial functional redundancy with eIF4GI limits interpretation of single knockdown\", \"Single lab per study\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Defined an essential in vivo function: EIF4G3 is specifically required to translate HSPA2 in spermatocytes, linking its loss to failed CDK1 activation and meiotic arrest.\",\n      \"evidence\": \"ENU repro8 mutant mice with western blot for HSPA2/CDK1 activity and RT-PCR confirming transcript presence\",\n      \"pmids\": [\"20430745\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How EIF4G3 selectively engages Hspa2 mRNA not defined\", \"Other meiotic mRNA targets not identified\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified phosphoregulation of EIF4G3 by CaMKI at Ser1156 as an activity-dependent switch promoting its selective entry into eIF4F to drive spine formation, establishing a signaling-to-translation mechanism unique to this isoform.\",\n      \"evidence\": \"In vitro kinase assays, S1156A phosphomutant, cap-affinity pulldown, RNAi, and spine-density imaging in neurons\",\n      \"pmids\": [\"22514323\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific mRNAs translated downstream not enumerated\", \"Structural basis of phospho-dependent recruitment unknown\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Showed EIF4G3 expression and isoform diversity are actively controlled — transcriptionally by DEAF1 and via alternative promoters/splicing/CUG initiation — with the EIF4G3 N-terminus contributing distinctly to initiation-factor assembly.\",\n      \"evidence\": \"Deaf1 KO/siRNA with polysome profiling; 5'RACE, RT-PCR and rescue of double-knockdown cells with defined isoforms\",\n      \"pmids\": [\"22923498\", \"22909319\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional role of N-terminal extension mechanistically undefined\", \"Single lab per study\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Connected EIF4G3 to the cell cycle by identifying Cdk1-dependent N-terminal phosphorylation in mitosis and its localization to spindle, MTOC, and midbody, implying spatially regulated translation during division.\",\n      \"evidence\": \"Confocal microscopy and mobility-shift phosphorylation analysis in synchronized HeLa cells with Cdk1 inhibitor\",\n      \"pmids\": [\"24091728\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of mitotic phosphorylation not tested\", \"Single lab\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrated post-transcriptional control of EIF4G3 by miR-520c-3p, linking its abundance to global translation, proliferation, and senescence in cancer cells.\",\n      \"evidence\": \"miRNA overexpression, siRNA knockdown, colony-formation and xenograft assays\",\n      \"pmids\": [\"24497838\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct luciferase target validation only implied\", \"Single lab\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Localized EIF4G3 to the spermatocyte nucleus and the transcriptionally silent XY body, raising the possibility of pre-positioning translation complexes ahead of meiotic divisions.\",\n      \"evidence\": \"Immunofluorescence confocal microscopy and fractionation during spermatogenesis with XY body markers\",\n      \"pmids\": [\"29161344\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional role at the XY body inferred but not tested\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The transcriptome-wide set of mRNAs selectively dependent on EIF4G3 versus eIF4GI, and the structural basis by which phosphorylation and isoform N-termini gate its entry into eIF4F, remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No genome-wide EIF4G3-specific translatome\", \"No structural model of phospho-regulated eIF4F assembly\", \"Mechanism of mRNA selectivity (Hspa2, reinitiation substrates) unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [6, 12]},\n      {\"term_id\": \"GO:0045182\", \"supporting_discovery_ids\": [6, 7, 12]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [16]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [14]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [6, 12]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-72613\", \"supporting_discovery_ids\": []},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [6, 12, 10]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [0, 5]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [10, 16]}\n    ],\n    \"complexes\": [\"eIF4F\"],\n    \"partners\": [\"EIF4E\", \"HSPA2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}