EIF3J (eukaryotic translation initiation factor 3 subunit J) is a cytoplasmic accessory subunit of the 13-subunit eIF-3 complex, the largest eukaryotic translation initiation factor. eIF-3 associates with the 40S ribosomal subunit and orchestrates several steps of cap-dependent translation initiation, promoting recruitment of eIF-1, eIF-1A, the eIF-2-GTP-Met-tRNAi ternary complex and eIF-5 to form the 43S pre-initiation complex, stimulating mRNA recruitment and scanning to the AUG start codon, and contributing to disassembly/recycling of post-termination ribosomal complexes while preventing premature 40S-60S subunit joining. EIF3J is a loosely associated, sub-stoichiometric ("labile") subunit that docks onto the complex through EIF3B; it positions near the 40S mRNA entry channel/decoding region and is required for stable binding of eIF-3 (and its subcomplexes) to the 40S subunit, thereby modulating mRNA loading and 40S availability. It is a non-catalytic accessory factor (its initiation-factor activity is contributed in the context of the assembled complex) and is phosphorylated in a serum-stimulation-dependent manner.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005852 eukaryotic translation initiation factor 3 complex | IBA GO_REF:0000033 | ACCEPT | Summary: EIF3J is a (labile) subunit of the eIF-3 complex, well supported across eukaryotes and by direct human evidence. This is the core cellular-component annotation. Reason: EIF3J is documented as a component of the 13-subunit eIF-3 complex, binding via EIF3B; the IBA is corroborated by IDA/IPI evidence. Supporting Evidence: file:human/EIF3J/EIF3J-uniprot.txt Component of the eukaryotic translation initiation factor 3 (eIF-3) complex |
| GO:0001732 formation of cytoplasmic translation initiation complex | IEA GO_REF:0000104 | ACCEPT | Summary: As part of eIF-3, EIF3J participates in assembly of the 43S/48S translation initiation complexes on the 40S subunit. A genuine core process annotation. Reason: eIF-3 facilitates recruitment of initiation factors and ternary complex to form the 43S PIC; EIF3J contributes to this assembly. Supporting Evidence: file:human/EIF3J/EIF3J-uniprot.txt facilitates the recruitment of eIF-1, eIF-1A, eIF-2:GTP:methionyl-tRNAi and eIF-5 to |
| GO:0002183 cytoplasmic translational initiation | IEA GO_REF:0000104 | ACCEPT | Summary: EIF3J participates in cytoplasmic translation initiation as an eIF-3 subunit. This is the core biological process. Reason: eIF-3 is required for several steps in initiation of protein synthesis; this is EIF3J's central biological role. Supporting Evidence: file:human/EIF3J/EIF3J-uniprot.txt required for several steps in the initiation of protein synthesis |
| GO:0003743 translation initiation factor activity | IEA GO_REF:0000120 | ACCEPT | Summary: EIF3J contributes translation initiation factor activity as an accessory subunit of eIF-3. The activity is exerted in the context of the assembled complex rather than by EIF3J alone. Reason: The core molecular function of EIF3J is translation initiation factor activity via the eIF-3 complex; note the curated experimental annotations use the contributes_to qualifier, reflecting its accessory role. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0003743 translation initiation factor activity molecular_function ECO:0000501 IEA |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: EIF3J is cytoplasmic, consistent with its role in cytoplasmic translation initiation. Reason: Cytoplasm is the documented subcellular location and the site of translation initiation. Supporting Evidence: file:human/EIF3J/EIF3J-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005852 eukaryotic translation initiation factor 3 complex | IEA GO_REF:0000120 | ACCEPT | Summary: Electronic transfer of eIF-3 complex membership, redundant with the IBA/IDA/IPI evidence. Reason: Correct core cellular component, corroborated by stronger evidence. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005852 eukaryotic translation initiation factor 3 complex cellular_component ECO:0000501 IEA |
| GO:0016282 eukaryotic 43S preinitiation complex | IEA GO_REF:0000104 | KEEP AS NON CORE | Summary: Via eIF-3, EIF3J is part of the transient 43S pre-initiation complex on the 40S subunit. A genuine but transient assembly intermediate. Reason: The 43S PIC is a transient initiation intermediate that contains eIF-3; a real but non-core localization relative to the stable eIF-3 complex membership. Supporting Evidence: file:human/EIF3J/EIF3J-uniprot.txt to form the 43S pre-initiation complex (43S PIC) |
| GO:0033290 eukaryotic 48S preinitiation complex | IEA GO_REF:0000104 | KEEP AS NON CORE | Summary: Via eIF-3, EIF3J is part of the transient 48S pre-initiation complex (after mRNA recruitment and start-codon scanning). A transient assembly intermediate. Reason: The 48S PIC is a transient initiation intermediate; real but non-core relative to stable eIF-3 complex membership. Supporting Evidence: file:human/EIF3J/EIF3J-uniprot.txt stimulates mRNA recruitment to the 43S PIC and scanning of the mRNA for |
| GO:0005515 protein binding | IPI PMID:14688252 The j-subunit of human translation initiation factor eIF3 is... | KEEP AS NON CORE | Summary: Interaction with EIF3B (P55884), the subunit through which EIF3J docks onto eIF-3; this study shows EIF3J is required for stable binding of eIF-3 to 40S subunits. Deep-research synthesis further localizes EIF3J binding to the 40S near the mRNA entry channel and A-site, where it binds anti-cooperatively with mRNA and acts as a gatekeeper for mRNA accommodation. Bare protein binding is uninformative, but the interaction is biologically central. Reason: Records the functionally important EIF3J-EIF3B interaction, but the term is uninformative; the informative function (eIF-3 membership and 40S/mRNA-entry-channel binding) is captured by complex/initiation annotations and core_functions. Supporting Evidence: PMID:14688252 j-subunit of human translation initiation factor eIF3 is required for the stable binding of eIF3 and its subcomplexes to 40 S ribosomal subunits in vitro file:human/EIF3J/EIF3J-deep-research-falcon.md Binds the 40S small subunit near the mRNA entry channel and A-site; competes anti-cooperatively with accommodated mRNA |
| GO:0005515 protein binding | IPI PMID:16932749 p97/DAP5 is a ribosome-associated factor that facilitates pr... | KEEP AS NON CORE | Summary: Interaction reported in a study of the ribosome-associated factor p97/DAP5. Bare protein binding is uninformative. Reason: Records a real interaction but uninformative term; not core to EIF3J's function. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:16932749 UniProtKB:Q04637 |
| GO:0005515 protein binding | IPI PMID:18628297 Human DDX3 functions in translation and interacts with the t... | KEEP AS NON CORE | Summary: Interaction with EIF4G1 (Q04637) in a study of DDX3 in translation and eIF3. Bare protein binding is uninformative. Reason: Records a real translation-related interaction but uninformative term; not core. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:18628297 UniProtKB:P55884 |
| GO:0005515 protein binding | IPI PMID:22113938 A bead-based approach for large-scale identification of in v... | KEEP AS NON CORE | Summary: Interaction with the casein kinase 2 catalytic subunit CSNK2A1 (P68400) from a kinase-substrate screen; consistent with EIF3J being phosphorylated. Bare protein binding is uninformative. Reason: Records a kinase-substrate interaction (EIF3J is phosphorylated) but uninformative term; not a core function. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:22113938 UniProtKB:P68400 |
| GO:0005515 protein binding | IPI PMID:25852190 Integrative analysis of kinase networks in TRAIL-induced apo... | KEEP AS NON CORE | Summary: Interaction with CSNK2A1 (P68400) from a kinase-network apoptosis study. Bare protein binding is uninformative. Reason: Records a kinase interaction but uninformative term; not core. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:25852190 UniProtKB:P68400 |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | KEEP AS NON CORE | Summary: HuRI binary interactome capturing an EIF3J-ABCE1 (P61221) interaction. ABCE1 is the ribosome-recycling ATPase; deep-research synthesis indicates EIF3J specifically (not merely the eIF-3 holo-complex) functionally couples to ABCE1/RLI1 and enhances post-termination ribosome recycling, so this interaction is biologically meaningful even though the bare term is uninformative. Reason: Records a recycling-relevant interaction (ABCE1) with EIF3J-subunit-specific functional support in the recycling literature, but the term itself is uninformative; the recycling role is captured at the complex level. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:32296183 UniProtKB:P61221 file:human/EIF3J/EIF3J-deep-research-falcon.md physically/ functionally associates with ABCE1/RLI1, the ATPase required for post-termination ribosome recycling |
| GO:0005515 protein binding | IPI PMID:32707033 Kinase Interaction Network Expands Functional and Disease Ro... | KEEP AS NON CORE | Summary: Interaction with CSNK2A1 (P68400) from a kinase-interaction-network study. Bare protein binding is uninformative. Reason: Records a kinase interaction but uninformative term; not core. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:32707033 UniProtKB:P68400 |
| GO:0005515 protein binding | IPI PMID:32911434 A functionally defined high-density NRF2 interactome reveals... | KEEP AS NON CORE | Summary: Interaction with NFE2L2/NRF2 (Q16236) from an NRF2-interactome screen. Bare protein binding is uninformative and likely peripheral. Reason: Records a real interaction but uninformative term and peripheral to translation initiation; not core. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:32911434 UniProtKB:Q16236 |
| GO:0005515 protein binding | IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling... | KEEP AS NON CORE | Summary: BioPlex affinity-purification capturing an EIF3J-CSNK2A1 (P68400) interaction. Bare protein binding is uninformative. Reason: Records a kinase interaction but uninformative term; not core. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:33961781 UniProtKB:P68400 |
| GO:0005515 protein binding | IPI PMID:35271311 OpenCell: Endogenous tagging for the cartography of human ce... | KEEP AS NON CORE | Summary: OpenCell endogenous-tagging interactome capturing EIF3J interactions with EIF3B (P55884) and ABCE1 (P61221), consistent with eIF-3 docking and recycling roles. Bare protein binding is uninformative. Reason: Records biologically consistent interactions (EIF3B, ABCE1) but uninformative term; captured by complex/initiation annotations. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:35271311 UniProtKB:P55884 |
| GO:0042802 identical protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | KEEP AS NON CORE | Summary: EIF3J self-interaction reported in the HuRI binary interactome (consistent with the EIF3J-EIF3J IntAct entry). A real homotypic interaction but not a core function. Reason: Records a self-interaction; not part of the core translation-initiation function. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0042802 identical protein binding molecular_function ECO:0000353 IPI PMID:32296183 UniProtKB:O75822 |
| GO:0001732 formation of cytoplasmic translation initiation complex | NAS PMID:16920360 eIF3: a versatile scaffold for translation initiation comple... | ACCEPT | Summary: Author statement (eIF3 review) that eIF-3 serves as a scaffold for assembly of translation initiation complexes; EIF3J participates as a subunit. Reason: Consistent with eIF-3's documented role in initiation-complex assembly; core process for EIF3J as a subunit. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0001732 formation of cytoplasmic translation initiation complex biological_process ECO:0005547 NAS PMID:16920360 |
| GO:0005852 eukaryotic translation initiation factor 3 complex | IPI PMID:17322308 Structural characterization of the human eukaryotic initiati... | ACCEPT | Summary: Direct (ComplexPortal/MS) evidence placing EIF3J in the eIF-3 complex. Core cellular component. Reason: Mass-spectrometry characterization of human eIF-3 confirms EIF3J as a component. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005852 eukaryotic translation initiation factor 3 complex cellular_component ECO:0000353 IPI PMID:17322308 |
| GO:0005829 cytosol | TAS Reactome:R-HSA-156808 | ACCEPT | Summary: Reactome curated cytosolic localization for translation-initiation reactions. Reason: Correct cytosolic localization, consistent with the cytoplasmic site of action. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005829 cytosol cellular_component ECO:0000304 TAS Reactome:R-HSA-156808 |
| GO:0005829 cytosol | TAS Reactome:R-HSA-156823 | ACCEPT | Summary: Reactome curated cytosolic localization, redundant with the other cytosol annotations. Reason: Correct cytosolic localization. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005829 cytosol cellular_component ECO:0000304 TAS Reactome:R-HSA-156823 |
| GO:0005829 cytosol | TAS Reactome:R-HSA-157849 | ACCEPT | Summary: Reactome curated cytosolic localization, redundant with the other cytosol annotations. Reason: Correct cytosolic localization. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005829 cytosol cellular_component ECO:0000304 TAS Reactome:R-HSA-157849 |
| GO:0005829 cytosol | TAS Reactome:R-HSA-72619 | ACCEPT | Summary: Reactome curated cytosolic localization, redundant with the other cytosol annotations. Reason: Correct cytosolic localization. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005829 cytosol cellular_component ECO:0000304 TAS Reactome:R-HSA-72619 |
| GO:0005829 cytosol | TAS Reactome:R-HSA-72621 | ACCEPT | Summary: Reactome curated cytosolic localization, redundant with the other cytosol annotations. Reason: Correct cytosolic localization. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005829 cytosol cellular_component ECO:0000304 TAS Reactome:R-HSA-72621 |
| GO:0005829 cytosol | TAS Reactome:R-HSA-72676 | ACCEPT | Summary: Reactome curated cytosolic localization, redundant with the other cytosol annotations. Reason: Correct cytosolic localization. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005829 cytosol cellular_component ECO:0000304 TAS Reactome:R-HSA-72676 |
| GO:0005829 cytosol | TAS Reactome:R-HSA-72691 | ACCEPT | Summary: Reactome curated cytosolic localization, redundant with the other cytosol annotations. Reason: Correct cytosolic localization. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005829 cytosol cellular_component ECO:0000304 TAS Reactome:R-HSA-72691 |
| GO:0005829 cytosol | TAS Reactome:R-HSA-72697 | ACCEPT | Summary: Reactome curated cytosolic localization, redundant with the other cytosol annotations. Reason: Correct cytosolic localization. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005829 cytosol cellular_component ECO:0000304 TAS Reactome:R-HSA-72697 |
| GO:0003743 translation initiation factor activity | IC PMID:17322308 Structural characterization of the human eukaryotic initiati... | ACCEPT | Summary: Curator-inferred (from eIF-3 complex membership) that EIF3J contributes to translation initiation factor activity. The contributes_to qualifier correctly reflects its accessory role within the complex. Reason: This is the core molecular function annotation for EIF3J, appropriately qualified as contributes_to for a non-catalytic accessory subunit. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0003743 translation initiation factor activity molecular_function ECO:0000305 IC PMID:17322308 |
| GO:0003743 translation initiation factor activity | IC PMID:18599441 Mass spectrometry reveals modularity and a complete subunit ... | ACCEPT | Summary: Curator-inferred translation initiation factor activity from eIF-3 complex membership (subunit interaction map study). Redundant with the other IC annotation. Reason: Core molecular function, appropriately qualified contributes_to. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0003743 translation initiation factor activity molecular_function ECO:0000305 IC PMID:18599441 |
| GO:0005852 eukaryotic translation initiation factor 3 complex | IDA PMID:17322308 Structural characterization of the human eukaryotic initiati... | ACCEPT | Summary: Direct MS-based evidence for EIF3J as an eIF-3 component. Core cellular component. Reason: Directly demonstrated eIF-3 complex membership. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005852 eukaryotic translation initiation factor 3 complex cellular_component ECO:0000314 IDA PMID:17322308 |
| GO:0005852 eukaryotic translation initiation factor 3 complex | IDA PMID:18599441 Mass spectrometry reveals modularity and a complete subunit ... | ACCEPT | Summary: Direct MS-based evidence for EIF3J as an eIF-3 component (subunit interaction map). Core cellular component. Reason: Directly demonstrated eIF-3 complex membership. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0005852 eukaryotic translation initiation factor 3 complex cellular_component ECO:0000314 IDA PMID:18599441 |
| GO:0006413 translational initiation | IC PMID:17322308 Structural characterization of the human eukaryotic initiati... | ACCEPT | Summary: Curator-inferred involvement in translational initiation from eIF-3 membership. Core biological process. Reason: EIF3J participates in translation initiation as an eIF-3 subunit. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0006413 translational initiation biological_process ECO:0000305 IC PMID:17322308 |
| GO:0006413 translational initiation | IC PMID:18599441 Mass spectrometry reveals modularity and a complete subunit ... | ACCEPT | Summary: Curator-inferred involvement in translational initiation from eIF-3 membership. Redundant with the other IC annotation. Reason: Core biological process for EIF3J as an eIF-3 subunit. Supporting Evidence: file:human/EIF3J/EIF3J-goa.tsv GO:0006413 translational initiation biological_process ECO:0000305 IC PMID:18599441 |
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Download this section (compressed HTML)Q: Does human EIF3J have a distinct, separable role in 40S ribosome recycling/availability (post-termination) versus initiation, as suggested by yeast Hcr1?
Q: How does the sub-stoichiometric/labile association of EIF3J with eIF-3 regulate switching between mRNA-entry-channel occupancy and mRNA loading?
Q: What is the functional consequence of serum-stimulated phosphorylation of EIF3J for its association with eIF-3 and selective mRNA translation?
Experiment: Selective EIF3J depletion/rescue with ribosome profiling and 40S/80S subunit-availability assays to dissect its contribution to initiation versus post-termination recycling.
Experiment: Cryo-EM of 40S-eIF-3 complexes with and without EIF3J to define its occupancy of the mRNA entry channel and effect on mRNA accommodation.
Experiment: Phosphomutant (phospho-null/phospho-mimetic) EIF3J variants to test how serum-stimulated phosphorylation modulates eIF-3 binding and translational output.
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