Affinage

EIF5B

Eukaryotic translation initiation factor 5B · UniProt O60841

Length
1220 aa
Mass
138.8 kDa
Annotated
2026-06-09
100 papers in source corpus 36 papers cited in narrative 36 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

EIF5B is a universally conserved ribosome-dependent GTPase (the eukaryotic homolog of bacterial IF2) that catalyzes the second GTP-dependent step of translation initiation, joining the 40S and 60S subunits into an elongation-competent 80S ribosome (PMID:10659855, PMID:9624054). It is a multidomain, 'chalice-shaped' GTPase whose GTP binding triggers a Switch-2 conformational change amplified through a molecular lever to the C-terminal tRNA-binding domain IV, and ITC/crystallographic work resolves this as a domain-release mechanism that activates the factor for subunit joining (PMID:11114334, PMID:24686316). Within the late initiation complex, eIF5B contacts both subunits across the intersubunit cleft and, through eukaryote-specific contacts with eIF1A via domain IV, remodels the 48S complex to reorient initiator Met-tRNAiMet into a conformation compatible with subunit joining (PMID:10982835, PMID:35732735, PMID:17568775). Its GTPase activity (requiring catalytic Asp-759) is mechanistically uncoupled from the physical joining step and instead functions as a fidelity checkpoint: an interdomain communication network senses correct P-site tRNA occupancy and transmits it to the GTPase center, and GTP hydrolysis drives eIF5B dissociation from a naturally long-lived 80S intermediate to license the initiation-to-elongation transition (PMID:12507428, PMID:12471154, PMID:31534220, PMID:33024099, PMID:31900355). Beyond canonical initiation, eIF5B coordinates with eIF5 and eIF1A — eIF5 competes with eIF1A for eIF5B binding with ~100-fold higher affinity — and contributes to start-codon selection and tRNA stabilization at non-optimal codons (PMID:25260592, PMID:30211544). eIF5B also drives non-canonical, eIF2-independent translation under stress and hypoxia, supporting cap-dependent hypoxic translation and ISR/uORF-regulated mRNAs such as ATF4 and PD-L1, and cap-independent IRES-driven survival proteins (PMID:32984844, PMID:29298419, PMID:30551605). Its activity is regulated by interacting partners including the translational repressor Puf6p and the DEAD-box helicase Vasa in germline mRNA control (PMID:18413716, PMID:15280213).

Mechanistic history

Synthesis pass · year-by-year structured walk · 17 steps
  1. 1971 High

    Established the founding biochemical role of the IF2 lineage by showing it forms a GTP/initiator-tRNA ternary complex that delivers tRNA to the small subunit, defining the central activity later inherited by eIF5B.

    Evidence In vitro ternary complex formation and ribosome assembly with puromycin reactivity (bacterial IF2)

    PMID:4943554

    Open questions at the time
    • Bacterial system; eukaryotic eIF5B role in tRNA delivery vs joining not yet distinguished
    • No structural mechanism
  2. 1998 High

    Identified the eukaryotic factor (yeast Fun12p/eIF5B) and showed it promotes Met-tRNAiMet binding to ribosomes in general initiation, connecting the conserved IF2 activity to eukaryotic translation.

    Evidence In vitro Met-tRNA binding plus in vivo genetic complementation in S. cerevisiae

    PMID:9624054

    Open questions at the time
    • Subunit-joining role not yet defined
    • No GTPase mechanism established
  3. 2000 High

    Defined eIF5B as the GTPase that catalyzes 40S+60S→80S subunit joining and demonstrated cross-species conservation, establishing its core function distinct from eIF2.

    Evidence Reconstituted in vitro subunit joining and GTPase assays; human factor plus archaeal IF2 complementation in yeast

    PMID:10200264 PMID:10659855

    Open questions at the time
    • Structural basis of GTPase coupling unknown
    • Timing/residence on ribosome unresolved
  4. 2000 High

    Provided the structural framework — a four-domain chalice GTPase in which GTP binding propagates a Switch-2 change ~90 Å to domain IV — explaining how nucleotide state controls ribosome binding.

    Evidence X-ray crystallography of IF2/eIF5B in apo, GDP, and GTP states

    PMID:11114334

    Open questions at the time
    • Conformations captured free, not on the ribosome
    • Hydrolysis trigger not defined
  5. 2000 High

    Mapped the eIF1A–eIF5B interaction to eIF5B domain IV and showed it is required for translation and growth, identifying a key partner that positions eIF5B in the initiation complex.

    Evidence Two-hybrid, reciprocal Co-IP, in vitro binding, and yeast genetics with truncation mutants

    PMID:10982835

    Open questions at the time
    • Structural detail of the interface unknown
    • Functional consequence on tRNA reorientation not yet shown
  6. 2002 High

    Dissected the GTPase as a checkpoint rather than a motor: Switch-I and active-site (Asp-759) mutations uncouple GTP hydrolysis from the mechanical joining step, showing hydrolysis gates 80S assembly fidelity.

    Evidence Active-site and Switch-I mutagenesis, intragenic suppressors, XTP substitution, in vitro joining/translation and yeast genetics

    PMID:12471154 PMID:12507428

    Open questions at the time
    • What the GTPase senses to trigger hydrolysis unknown
    • Residence time on 80S unmeasured
  7. 2007 High

    Placed eIF5B physically in the intersubunit cleft, defining domain-specific rRNA/protein contacts that explain how a single factor bridges both subunits during joining.

    Evidence Directed hydroxyl-radical cleavage from tethered cysteines on 80S ribosomes

    PMID:17568775

    Open questions at the time
    • Low resolution relative to later cryo-EM
    • Dynamics during joining not captured
  8. 2011 High

    Showed eIF5B helix H12 acts as a structural 'ruler' linking the GTPase center to the P site, mechanically coupling tRNA positioning to subunit joining.

    Evidence H12 length/rigidity mutagenesis; in vitro joining, Met-tRNA stability, and in vivo leaky-scanning assays

    PMID:21335519

    Open questions at the time
    • Direct structural visualization of the relay awaited at the time
    • Quantitative link to hydrolysis timing unresolved
  9. 2014 High

    Refined the activation model (domain-release on GTP binding) and showed eIF5B cooperates with eIF5 to influence 48S formation and start-codon selection, extending its role beyond joining.

    Evidence Six crystal structures with ITC; in vitro 48S formation, toe-printing, and mutational analysis

    PMID:24686316 PMID:25260592

    Open questions at the time
    • Codon-selection role mechanistically partial
    • Coordination with eIF2-GDP release not yet defined
  10. 2019 High

    Demonstrated by real-time imaging that eIF5B has a long 80S residence and that GTP hydrolysis triggers its dissociation, defining a kinetic checkpoint for entry into elongation.

    Evidence Single-molecule fluorescence in reconstituted yeast translation with non-hydrolyzable GTP analogs

    PMID:31534220

    Open questions at the time
    • Atomic conformational state of the checkpoint not resolved here
    • Sensor for P-site occupancy not identified
  11. 2020 High

    Provided atomic structures of the 80S-eIF5B intermediate and identified the interdomain communication network (e.g. Y837–H480) that transmits P-site tRNA occupancy to the GTPase center, explaining the fidelity checkpoint.

    Evidence Cryo-EM of yeast and human 80S-eIF5B complexes with mutagenesis and in vitro/in vivo validation

    PMID:31900355 PMID:33024099

    Open questions at the time
    • Full kinetic trajectory of hydrolysis-to-release partly inferred
    • Human-specific regulatory contacts not fully enumerated
  12. 2022 High

    Captured the eIF1A–eIF5B remodeling of the 48S complex that reorients initiator tRNA for joining, defining the eukaryote-specific structural transition between the two GTPase steps.

    Evidence Single-particle cryo-EM and single-molecule fluorescence of the human reconstituted initiation system

    PMID:35732735

    Open questions at the time
    • Order of eIF5/eIF1A exchange in cells not directly observed
    • Regulation of the transition under stress unaddressed
  13. 2020 Medium

    Characterized partner-mediated and competitive regulation of eIF5B: eIF5 binds via a C-terminal motif and outcompetes eIF1A ~100-fold, while overlapping eIF1A–eIF5B interfaces are remodeled across initiation stages, building a model for coordinating the two GTPase steps.

    Evidence In vitro competition/affinity binding and NMR with mutational analysis

    PMID:27325746 PMID:30211544

    Open questions at the time
    • In-cell relevance of the affinity hierarchy not tested
    • Coupling to eIF2-GDP release inferred, not demonstrated
  14. 2020 High

    Established a non-canonical, eIF2-independent translation role for eIF5B in driving stress- and hypoxia-adaptive and immune-modulatory protein expression, expanding its biology beyond housekeeping initiation.

    Evidence CRISPR screen, MATRIX proteomics, polysome profiling, 5'UTR/uORF reporters, knockdown/overexpression (PD-L1, ATF4, hypoxic translatome)

    PMID:29298419 PMID:30551605 PMID:32984844

    Open questions at the time
    • How eIF5B selects specific uORF/IRES mRNAs unknown
    • Molecular switch between canonical and non-canonical modes undefined
  15. 2021 Medium

    Consolidated the survival role of eIF5B in cap-independent IRES and uORF-driven translation of anti-apoptotic mRNAs during the stress response in cancer cells.

    Evidence IRES reporters, polysome profiling, siRNA knockdown, caspase assays (glioblastoma); plus review synthesis

    PMID:30670698 PMID:34512736

    Open questions at the time
    • Review entry (34512736) adds no primary data
    • Direct mechanism of IRES selection by eIF5B not defined
    • Cell-context specificity unresolved
  16. 2008 Medium

    Identified physiological and pathological regulators acting through eIF5B: the repressor Puf6p blocks 48S→80S conversion of ASH1 mRNA, and enteroviral 3C protease cleaves eIF5B to contribute to host translational shutoff.

    Evidence Yeast in vitro translation, Co-IP and phospho-site mutagenesis (Puf6p); in vitro and infected-cell cleavage assays (3C protease)

    PMID:18413716 PMID:18572216

    Open questions at the time
    • Generality of Puf6p-type repression beyond ASH1 unclear
    • Functional contribution of 3C cleavage to viral fitness not quantified
  17. 2014 Medium

    Linked eIF5B abundance to cell-state control, with eIF5B limiting translation in quiescent/arrested states and its level tuning cell-cycle exit and oocyte maturation.

    Evidence siRNA knockdown, overexpression, tRNA-Meti Co-IP, Xenopus oocyte and cell-cycle assays

    PMID:25261552

    Open questions at the time
    • Single-lab functional model with partial mechanism
    • Direct molecular cause of state-specific limitation unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • How eIF5B is switched between canonical 80S-joining and selective stress/IRES/uORF translation, and how it recognizes specific regulatory mRNAs, remains unresolved.
  • No defined molecular determinant for non-canonical mRNA selection
  • No structure of eIF5B engaging an IRES or stress-specific complex
  • Regulatory post-translational modifications of human eIF5B in stress uncharacterized

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003924 GTPase activity 5 GO:0045182 translation regulator activity 5 GO:0003723 RNA binding 3 GO:0060089 molecular transducer activity 3 GO:0140657 ATP-dependent activity 2
Localization
GO:0005840 ribosome 4 GO:0005829 cytosol 2
Pathway
R-HSA-392499 Metabolism of proteins 3 R-HSA-8953854 Metabolism of RNA 3 R-HSA-8953897 Cellular responses to stimuli 3
Partners
EIF1AEIF5PUF6 (PUF6P)RPLP1/L12 STALKTRNA-IMETVASA
Complex memberships
48S pre-initiation complex80S ribosome initiation complex

Evidence

Reading pass · 36 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2000 eIF5B (human IF2 homolog) is essential for ribosomal subunit joining (40S+60S → 80S) in eukaryotes and possesses a ribosome-dependent GTPase activity required for this function. In vitro reconstituted translation assay with purified factors; ribosomal subunit joining assay; GTPase assay Nature High 10659855
2000 Crystal structures of IF2/eIF5B in free, GDP-bound, and GTP-bound states reveal a 'chalice-shaped' GTPase with four conserved domains; GTP binding induces a conformational change in Switch 2 that is amplified ~90 Å via a molecular lever to domain IV, explaining GTPase function and ribosome binding. X-ray crystallography in three nucleotide states Cell High 11114334
1998 Yeast eIF5B (yIF2/Fun12p) promotes Met-tRNAiMet binding to ribosomes, functioning in general translation initiation, as demonstrated by molecular genetic and biochemical assays in S. cerevisiae. In vitro Met-tRNA binding assay; in vivo genetic complementation in yeast Science High 9624054
1999 Human eIF5B functions as a translation factor that facilitates proper binding of initiator Met-tRNA to the ribosomal P site, and archaeal IF2 can substitute for yeast eIF5B both in vivo and in vitro, demonstrating universal conservation. In vitro translation assay; in vivo complementation (yeast); in vitro subunit joining assay Proceedings of the National Academy of Sciences of the United States of America High 10200264
2002 eIF5B Switch I mutations impair GTP hydrolysis and general translation but not subunit joining per se; intragenic suppressors restore translation without restoring GTPase activity, uncoupling GTPase activity from the mechanical subunit-joining function. eIF5B GTP hydrolysis functions as a checkpoint for 80S assembly. Site-directed mutagenesis; intragenic suppressor screen; in vitro translation and subunit joining assays; yeast genetics Cell High 12507428
2002 eIF5B GTPase activity (requiring hydrolysis at conserved Asp-759) catalyzes a second GTP-dependent step in eukaryotic translation initiation, distinct from eIF2 GTPase, required for subunit joining and translation. Mutation D759N converts eIF5B to an XTPase, introducing an XTP requirement for subunit joining. Active-site mutagenesis (D759N); in vitro subunit joining assay; in vitro translation assay with XTP substitution Proceedings of the National Academy of Sciences of the United States of America High 12471154
2000 eIF1A and eIF5B interact directly; the eIF1A binding site maps to the C-terminal region (domain IV) of eIF5B. This interaction is critical for growth in vivo and for translation in vitro; overexpression of eIF1A exacerbates slow-growth of C-terminally truncated eIF5B strains. Two-hybrid assay; coimmunoprecipitation; in vitro binding assay; yeast genetics (overexpression, truncation mutants) Molecular and cellular biology High 10982835
2008 Puf6p represses ASH1 mRNA translation by blocking conversion of 48S to 80S complex through direct interaction with eIF5B (Fun12p); this interaction requires the Puf6p PUF domain and is RNA-dependent. CK2 phosphorylation of Puf6p at Ser31/Ser34/Ser35 relieves this repression. Yeast extract-based in vitro translation assay; coimmunoprecipitation; site-directed mutagenesis of phosphorylation sites; kinase inhibition experiments Genes & development High 18413716
2004 Vasa (DEAD-box helicase) interacts physically with eIF5B (dIF2) in Drosophila; reduction of Vasa-eIF5B interaction causes female sterility, loss of Gurken protein accumulation (indicating failure to translationally regulate grk mRNA), and abolishes germ cell formation. Site-directed mutagenesis of vas; yeast two-hybrid; genetic analysis of vas alleles affecting eIF5B interaction; immunostaining for Gurken protein Development (Cambridge, England) High 15280213
2019 eIF5B has a long residence time on the 80S ribosome after subunit joining; inhibition of eIF5B GTPase activity after subunit joining prevents eIF5B dissociation from 80S and blocks entry into elongation. eIF5B dissociation serves as a kinetic checkpoint for the initiation-to-elongation transition, triggered by ribosome conformational change. Single-molecule fluorescence microscopy in reconstituted yeast translation system; GTPase inhibition with non-hydrolyzable GTP analogs Nature High 31534220
2022 Cryo-EM structure of human 48S initiation complex containing both eIF1A and eIF5B reveals eukaryote-specific contacts between eIF1A and eIF5B that remodel the initiation complex, reorienting the initiator aminoacyl-tRNA into a conformation compatible with subunit joining. Single-molecule fluorescence defined the timing of eIF1A and eIF5B association/departure. Single-particle cryo-EM; single-molecule fluorescence; in vitro reconstituted human translation system Nature High 35732735
2020 Cryo-EM structure of 80S-eIF5B complex with Met-tRNAiMet just before elongation reveals a eukaryote-specific fidelity checkpoint implemented by eIF5B in concert with large ribosomal subunit components; long eIF5B residence exploited to capture this naturally long-lived intermediate. Cryo-EM structure determination; single-molecule fluorescence-guided sample preparation Nature communications High 33024099
2020 Cryo-EM structure of yeast 80S-eIF5B with non-hydrolyzable GTP analog reveals that a stretch of residues near the γ-phosphate including universally conserved Y837 contacts catalytic H480; mutagenesis confirmed these residues regulate ribosome binding, GTP hydrolysis, and translation initiation. Long-range interdomain communications transmit P-site tRNA occupancy to the GTPase center. Cryo-EM at 3.6 Å; site-directed mutagenesis; in vitro translation; in vivo yeast growth assays Proceedings of the National Academy of Sciences of the United States of America High 31900355
2022 Cryo-EM structures of 70S-IC from Pseudomonas aeruginosa with compact GDP-bound IF2 show that GDP binding induces rotation of Switch 2 α-helix in the G domain, triggering large domain movements that relocate the C2 (tRNA-binding) domain 35 Å away from initiator tRNA, explaining how IF2 releases tRNA to allow fMet-tRNAifMet accommodation and transition to elongation. Cryo-EM structure determination Nature communications High 35697706
2014 Six crystal structures of eIF5B in apo, GDP-, and GTP-bound forms show GTP binding induces conformational changes in switch regions, domain II rotation relative to G domain, and release of domain III from switch 2 contacts, increasing intrinsic flexibility. A 'domain release mechanism' is proposed for eIF5B/IF2 activation during subunit joining. X-ray crystallography (six structures); isothermal titration calorimetry for nucleotide binding thermodynamics The EMBO journal High 24686316
2007 eIF5B is positioned in the intersubunit cleft of the 80S ribosome: domain I near the GTPase activating center of 60S; domain II contacts 40S (18S rRNA helices 3, 5, base of helix 15, rpS23); domain III contacts H95 of 28S rRNA and helix 44 of 18S rRNA; domain IV near the peptidyl-transferase center contacting rpL10E. eIF5B binding may induce conformational changes in both subunits. Directed hydroxyl radical cleavage (Fe-EDTA tethered to engineered cysteines in eIF5B) on 80S ribosomes The EMBO journal High 17568775
2014 eIF5B and eIF5 together stimulate 48S initiation complex formation and influence initiation codon selection during ribosomal scanning. eIF5B stabilizes initiator tRNA in the 40S P-site after eIF2-GDP dissociation at non-optimal start codons. Mutational analysis revealed distinct roles for eIF5B in 48S IC formation versus subunit joining. In vitro 48S initiation complex formation assays; toe-printing; mutational analysis of eIF1A and eIF5B Nucleic acids research High 25260592
2011 The α-helix H12 of eIF5B functions as a structural 'ruler' connecting the GTPase center to the P site. Shortening H12 by six residues or substituting six residues with Gly impairs the rate of subunit joining in vitro and reduces stability of Met-tRNA(i)Met binding in 80S complexes, impairing yeast growth and enhancing leaky scanning in vivo. Site-directed mutagenesis (H12 length and rigidity variants); in vitro subunit joining assay; in vivo yeast growth assay; ribosome leaky scanning assay RNA High 21335519
2020 eIF5B drives ISR-dependent translation of PD-L1 in lung cancer; impairment of heme biosynthesis activates ISR, enabling bypass of inhibitory uORFs in the PD-L1 5' UTR and requiring eIF5B for enhanced PD-L1 translation. eIF5B overexpression alone is sufficient to induce PD-L1. CRISPR-based genetic screen; siRNA knockdown; polysome profiling; luciferase reporter assays with 5' UTR constructs; eIF5B overexpression Nature cancer High 32984844
2018 eIF5B is an essential component of the hypoxic cap-dependent translation machinery; in hypoxia, eIF5B associates more with translating ribosomes (demonstrated by MATRIX) and regulates translation of central carbon metabolism, hypoxic adaptation, and ATF4-mediated stress response mRNAs even when eIF2 is active. MATRIX (mass spectrometry of active translation factors by ribosome density fractionation and isotopic labeling); global translatome analysis; siRNA knockdown Cell reports High 29298419
2014 Upregulation of eIF5B acts as a limiting factor for translation in cell-cycle arrest states (G0, immature oocytes, ES cells). In serum-starved THP1 cells, increased eIF5B forms complexes with tRNA-Meti. eIF5B depletion hastens G0 arrest and reduces oocyte maturation; overexpression promotes oocyte maturation and causes cell death in serum-starved cells. siRNA knockdown; eIF5B overexpression; coimmunoprecipitation with tRNA-Meti; Xenopus oocyte maturation assays; cell cycle analysis Proceedings of the National Academy of Sciences of the United States of America Medium 25261552
2019 eIF5B promotes cap-independent IRES-mediated translation of antiapoptotic mRNAs (XIAP, Bcl-xL, cIAP1, c-FLIPS) and NRF2 in glioblastoma cells; eIF5B depletion sensitizes cells to TRAIL-induced apoptosis via caspases-8, -9, -7 and decreases NF-κB activation. siRNA knockdown of eIF5B; IRES reporter assays; polysome profiling; caspase activity assays; western blotting Cell death & disease Medium 30670698
2018 Human eIF5 interacts directly with eIF5B via a C-terminal eIF5B-binding motif; eIF5 competes with eIF1A for binding to eIF5B with ~100-fold higher affinity. This suggests eIF5 may coordinate the two GTPase steps by recruiting eIF5B to the PIC, and displacement of eIF5 by eIF1A may be coupled to eIF2-GDP release. In vitro binding assay; competition binding assay; affinity measurements Biochemistry Medium 30211544
2016 eIF1A and eIF5B have a second binding interface beyond the known eIF1A C-terminal tail/eIF5B-D4 contact; intramolecular interactions exist within eIF1A (folded domain vs CTT) and within eIF5B (D3 vs D4) that compete with the eIF1A-eIF5B interactions and are disrupted on the ribosome at different initiation stages. NMR; in vitro binding assays; mutational analysis Nucleic acids research Medium 27325746
2018 eIF5B cooperates with eIF1A and eIF5 to facilitate uORF2-mediated repression of ATF4 translation; eIF5B depletion de-represses ATF4 translation by a mechanism requiring the repressive uORF2, not eIF2α phosphorylation. siRNA knockdown; ATF4-luciferase reporter assay with uORF mutations; polysome profiling; western blotting International journal of molecular sciences Medium 30551605
2008 eIF5B is proteolytically cleaved by enterovirus 3C protease (from poliovirus, CVB, HRV) at a single site (VMEQG479 in human eIF5B) separating the N-terminal domain from the essential C-terminal GTPase and C-terminal domains, potentially contributing to translational shutoff in infected cells. In vitro cleavage of purified native eIF5B by recombinant 3Cpro; identification of cleavage site; detection of cleavage in infected cells by western blot Virology Medium 18572216
2013 The N-terminal domain of bacterial IF2 stabilizes interactions between IF2 and the L7/L12 stalk of the 50S subunit in the 70S IC (not the 30S IC); deletion of the N-domain impairs fMet-tRNA positioning and efficient transpeptidation. Fast kinetics and single-molecule data show the N-terminus promotes 70S IC formation by stabilizing productive 50S sampling. Small-angle X-ray diffraction; cryo-EM; fast kinetics (stopped-flow); single-molecule fluorescence; N-domain deletion mutants Proceedings of the National Academy of Sciences of the United States of America High 24029017
2006 L12 (ribosomal stalk protein) directly binds IF2, EF-Tu, EF-G, and RF3 via the same conserved region of the L12 C-terminal domain (involving K70, L80, E82). All four factors compete for the same L12 CTD binding site; L12 binds each factor with millimolar affinity in solution. Heteronuclear NMR spectroscopy; chemical shift mapping; competition binding Journal of molecular biology High 17070545
2010 L12 stalk protein on the 50S subunit is required for rapid IF2-GTP-dependent subunit association (~40-fold rate reduction on L12-depleted 50S), but L12 depletion does not affect individual rates of GTP hydrolysis on IF2, Pi release, or IF2 release. L12 is not a GAP for IF2. Fast kinetics (stopped-flow); L12 depletion from 50S subunits; GTP hydrolysis assay; Pi release assay; subunit association assay Journal of molecular biology High 20385143
2018 Complementary charge-based (salt bridge) interactions between positively charged residues of L12 CTD helices 4/5 and negatively charged residues of IF2 between G4 and G5 motifs are the molecular determinants of rapid subunit association. Charge-reversed compensatory double mutants (L12+IF2) significantly restore 70S IC formation rate and yield. Site-directed mutagenesis (15 L12 + 15 IF2 point mutants); stopped-flow subunit association assay; molecular dynamics simulations; charge-reversal rescue experiments Proceedings of the National Academy of Sciences of the United States of America High 29686090
2006 Bacterial IF2 interacts with the 30S subunit via two separate binding sites: the N-terminal domain provides a high-affinity 'anchoring' interaction (IF1- and GTP-independent), while the G3 subdomain of the G-domain provides the functional 'core' interaction for fMet-tRNA P-site decoding (IF1- and GTP-dependent). Deletion mutant analysis (IF2ΔN); in vitro fMet-tRNA binding; dipeptide formation assay; subunit binding assay under varying conditions Journal of molecular biology High 16935296
2000 The C-terminal subdomain IF2 C-2 (110 amino acids, Glu-632 to Ala-741 of B. stearothermophilus IF2) contains the entire fMet-tRNA binding site of IF2 with the same specificity and affinity as the full C-domain or intact IF2. The minimal fMet-tRNA binding fragment is 90 amino acids. Limited proteolysis; production of isolated subdomains; fMet-tRNA binding assay; CD; denaturation studies The Journal of biological chemistry High 10644698
1971 IF2 forms a ternary complex with GTP and fMet-tRNA(f) that functions as an intermediate in translation initiation, transferring both fMet-tRNA(f) and GTP to 30S ribosomal subunits in the presence of IF1 and an mRNA codon; the resulting 70S complex supports puromycin reactivity. In vitro ternary complex formation; filter binding; ribosome complex assembly; puromycin reaction Proceedings of the National Academy of Sciences of the United States of America High 4943554
2021 eIF5B promotes cap-independent translation of IRES-containing mRNAs encoding survival proteins (XIAP, Bcl-xL) and uORF-regulated mRNAs under stress conditions, functioning as a regulatory node for cancer cell survival during integrated stress response. Reviewed from prior experimental work (IRES reporter assays, polysome profiling, siRNA knockdown); review article summarizing established experimental findings Frontiers in genetics Low 34512736
2003 Bacterial IF2 is positioned in the 70S IC with G-domain residues near 16S rRNA helices H3, H4, H17, H18, and the C1/C2 domain junction near H89 and the thiostrepton region of 23S rRNA; IF2 orientation on 30S subunit changes during transition from 30S to 70S initiation complex. Chemical nuclease probing (Cu(II):1,10-orthophenanthroline and Fe(II):EDTA tethered to engineered Cys residues in IF2); rRNA cleavage mapping RNA High 12869707
2004 The IF2N domain (N-terminal ~6 kDa domain of E. coli IF2) is structurally independent, connected to the conserved C-terminal domains by a flexible linker, and tumbles independently as shown by NMR relaxation. Domains I-III have flexible/unstructured regions with helical content that decreases above 35°C. NMR spectroscopy (15N relaxation, chemical shift analysis); circular dichroism Protein science Medium 14691238

Source papers

Stage 0 corpus · 100 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2000 The joining of ribosomal subunits in eukaryotes requires eIF5B. Nature 325 10659855
2000 X-Ray structures of the universal translation initiation factor IF2/eIF5B: conformational changes on GDP and GTP binding. Cell 184 11114334
2006 The nucleotide-binding site of bacterial translation initiation factor 2 (IF2) as a metabolic sensor. Proceedings of the National Academy of Sciences of the United States of America 132 16968770
2004 Interaction with eIF5B is essential for Vasa function during development. Development (Cambridge, England) 125 15280213
2000 Chaperone properties of bacterial elongation factor EF-G and initiation factor IF2. The Journal of biological chemistry 119 10625618
1998 Promotion of met-tRNAiMet binding to ribosomes by yIF2, a bacterial IF2 homolog in yeast. Science (New York, N.Y.) 118 9624054
1987 Feedback regulation of rRNA synthesis in Escherichia coli. Requirement for initiation factor IF2. Journal of molecular biology 108 2448483
1984 Sequence of the initiation factor IF2 gene: unusual protein features and homologies with elongation factors. Proceedings of the National Academy of Sciences of the United States of America 108 6096856
2006 The ribosomal stalk binds to translation factors IF2, EF-Tu, EF-G and RF3 via a conserved region of the L12 C-terminal domain. Journal of molecular biology 106 17070545
2002 Uncoupling of initiation factor eIF5B/IF2 GTPase and translational activities by mutations that lower ribosome affinity. Cell 102 12507428
2020 eIF5B drives integrated stress response-dependent translation of PD-L1 in lung cancer. Nature cancer 100 32984844
2002 Initiation factor eIF5B catalyzes second GTP-dependent step in eukaryotic translation initiation. Proceedings of the National Academy of Sciences of the United States of America 89 12471154
1999 Universal conservation in translation initiation revealed by human and archaeal homologs of bacterial translation initiation factor IF2. Proceedings of the National Academy of Sciences of the United States of America 89 10200264
2008 Translation of ASH1 mRNA is repressed by Puf6p-Fun12p/eIF5B interaction and released by CK2 phosphorylation. Genes & development 87 18413716
2000 Physical and functional interaction between the eukaryotic orthologs of prokaryotic translation initiation factors IF1 and IF2. Molecular and cellular biology 77 10982835
2008 Cleavage of eukaryotic initiation factor eIF5B by enterovirus 3C proteases. Virology 72 18572216
1975 Cross-linking of initiation factor IF-2 to Escherichia coli 30 S ribosomal proteins with dimethylsuberimidate. The Journal of biological chemistry 66 805140
2019 eIF5B gates the transition from translation initiation to elongation. Nature 60 31534220
2000 The C-terminal subdomain (IF2 C-2) contains the entire fMet-tRNA binding site of initiation factor IF2. The Journal of biological chemistry 60 10644698
1982 Cloning and mapping of a gene for translational initiation factor IF2 in Escherichia coli. Proceedings of the National Academy of Sciences of the United States of America 59 6214789
2022 eIF5B and eIF1A reorient initiator tRNA to allow ribosomal subunit joining. Nature 58 35732735
1991 Molecular dissection of translation initiation factor IF2. Evidence for two structural and functional domains. The Journal of biological chemistry 58 1885570
1985 Two translational initiation sites in the infB gene are used to express initiation factor IF2 alpha and IF2 beta in Escherichia coli. The EMBO journal 58 3894004
1998 Initiation factors IF1 and IF2 synergistically remove peptidyl-tRNAs with short polypeptides from the P-site of translating Escherichia coli ribosomes. Journal of molecular biology 56 9698545
1987 The protein synthesis initiation factor 2 G-domain. Study of a functionally active C-terminal 65-kilodalton fragment of IF2 from Escherichia coli. Biochemistry 55 2444251
2006 Translation initiation factor IF2 interacts with the 30 S ribosomal subunit via two separate binding sites. Journal of molecular biology 54 16935296
1999 In vitro study of two dominant inhibitory GTPase mutants of Escherichia coli translation initiation factor IF2. Direct evidence that GTP hydrolysis is necessary for factor recycling. The Journal of biological chemistry 54 10037688
2013 Involvement of protein IF2 N domain in ribosomal subunit joining revealed from architecture and function of the full-length initiation factor. Proceedings of the National Academy of Sciences of the United States of America 50 24029017
1983 Organization of the Escherichia coli chromosome around the genes for translation initiation factor IF2 (infB) and a transcription termination factor (nusA). Journal of molecular biology 49 6306257
2007 Position of eukaryotic initiation factor eIF5B on the 80S ribosome mapped by directed hydroxyl radical probing. The EMBO journal 48 17568775
2003 Ribosomal localization of translation initiation factor IF2. RNA (New York, N.Y.) 47 12869707
1971 A complex between initiation factor IF2, guanosine triphosphate, and fMet-tRNA: an intermediate in initiation complex formation. Proceedings of the National Academy of Sciences of the United States of America 47 4943554
2014 eIF5B employs a novel domain release mechanism to catalyze ribosomal subunit joining. The EMBO journal 44 24686316
1986 Molecular cloning and sequence of the Bacillus stearothermophilus translational initiation factor IF2 gene. Molecular & general genetics : MGG 44 3025563
1992 Both forms of translational initiation factor IF2 (alpha and beta) are required for maximal growth of Escherichia coli. Evidence for two translational initiation codons for IF2 beta. Journal of molecular biology 42 1374802
2011 Bacterial ribosome requires multiple L12 dimers for efficient initiation and elongation of protein synthesis involving IF2 and EF-G. Nucleic acids research 40 22102582
2010 The ribosomal stalk plays a key role in IF2-mediated association of the ribosomal subunits. Journal of molecular biology 40 20385143
2017 Ribosomal protein L7/L12 is required for GTPase translation factors EF-G, RF3, and IF2 to bind in their GTP state to 70S ribosomes. The FEBS journal 39 28342293
2014 eIF5 and eIF5B together stimulate 48S initiation complex formation during ribosomal scanning. Nucleic acids research 39 25260592
2001 Modulation of ribosomal recruitment to 5'-terminal start codons by translation initiation factors IF2 and IF3. FEBS letters 38 11334885
2018 Oxygen-Sensitive Remodeling of Central Carbon Metabolism by Archaic eIF5B. Cell reports 37 29298419
1995 Mutants of Escherichia coli initiator tRNA defective in initiation. Effects of overproduction of methionyl-tRNA transformylase and the initiation factors IF2 and IF3. The Journal of biological chemistry 36 7538134
1994 Purification procedure for bacterial translational initiation factors IF2 and IF3. Protein expression and purification 35 8054843
2016 eIF1A/eIF5B interaction network and its functions in translation initiation complex assembly and remodeling. Nucleic acids research 33 27325746
2014 Upregulation of eIF5B controls cell-cycle arrest and specific developmental stages. Proceedings of the National Academy of Sciences of the United States of America 32 25261552
1998 Binding of Escherichia coli initiation factor IF2 to 30S ribosomal subunits: a functional role for the N-terminus of the factor. Biochemical and biophysical research communications 32 9826553
2020 Structural basis for the transition from translation initiation to elongation by an 80S-eIF5B complex. Nature communications 31 33024099
2019 Eukaryotic initiation factor 5B (eIF5B) provides a critical cell survival switch to glioblastoma cells via regulation of apoptosis. Cell death & disease 31 30670698
2018 Complementary charge-based interaction between the ribosomal-stalk protein L7/12 and IF2 is the key to rapid subunit association. Proceedings of the National Academy of Sciences of the United States of America 26 29686090
2016 eIF5B increases ASAP1 expression to promote HCC proliferation and invasion. Oncotarget 25 27694689
1998 A six-domain structural model for Escherichia coli translation initiation factor IF2. Characterisation of twelve surface epitopes. Biochemistry and molecular biology international 25 9861457
2019 Translation initiation factor IF2 contributes to ribosome assembly and maturation during cold adaptation. Nucleic acids research 24 30916323
1991 Superexpression and fast purification of E coli initiation factor IF2. Biochimie 24 1742367
1991 Tandem translation of E. coli initiation factor IF2 beta: purification and characterization in vitro of two active forms. Biochemical and biophysical research communications 23 1764105
2022 Compact IF2 allows initiator tRNA accommodation into the P site and gates the ribosome to elongation. Nature communications 21 35697706
2004 The N-terminal domain (IF2N) of bacterial translation initiation factor IF2 is connected to the conserved C-terminal domains by a flexible linker. Protein science : a publication of the Protein Society 21 14691238
2004 The Pseudomonas aeruginosa initiation factor IF-2 is responsible for formylation-independent protein initiation in P. aeruginosa. The Journal of biological chemistry 21 15385567
2001 Remarkable conservation of translation initiation factors: IF1/eIF1A and IF2/eIF5B are universally distributed phylogenetic markers. IUBMB life 20 11699879
2000 Interaction of fMet-tRNA(fMet) with the C-terminal domain of translational initiation factor IF2 from Bacillus stearothermophilus. FEBS letters 20 10767407
2007 Translation factor IF2 at the interface of transposition and replication by the PriA-PriC pathway. Molecular microbiology 19 18028309
1997 E. coli translation initiation factor IF2--an extremely conserved protein. Comparative sequence analysis of the infB gene in clinical isolates of E. coli. FEBS letters 19 9428651
2021 Established and Emerging Regulatory Roles of Eukaryotic Translation Initiation Factor 5B (eIF5B). Frontiers in genetics 18 34512736
2018 Human eIF5 and eIF1A Compete for Binding to eIF5B. Biochemistry 18 30211544
1992 OmpT proteolysis of E. coli initiation factor IF2. Elimination of a cleavage site by site-directed mutagenesis. Biochemistry international 18 1417895
2020 Long-range interdomain communications in eIF5B regulate GTP hydrolysis and translation initiation. Proceedings of the National Academy of Sciences of the United States of America 17 31900355
2011 Structural integrity of {alpha}-helix H12 in translation initiation factor eIF5B is critical for 80S complex stability. RNA (New York, N.Y.) 17 21335519
2000 Investigation of the translation-initiation factor IF2 gene, infB, as a tool to study the population structure of Streptococcus agalactiae. Microbiology (Reading, England) 17 10878130
1997 Translational initiation factor IF2 from Bacillus stearothermophilus: a spectroscopic and microcalorimetric study of the C-domain. Biochemistry 17 9115993
1994 In vivo study of engineered G-domain mutants of Escherichia coli translation initiation factor IF2. Molecular microbiology 17 8170391
1988 Identification, cloning and sequence of the Streptococcus faecium infB (translational initiation factor IF2) gene. Molecular & general genetics : MGG 17 3063954
2018 Eukaryotic Initiation Factor 5B (eIF5B) Cooperates with eIF1A and eIF5 to Facilitate uORF2-Mediated Repression of ATF4 Translation. International journal of molecular sciences 16 30551605
1990 Characterization of the translational start site for IF2 beta, a short form of Escherichia coli initiation factor IF2. European journal of biochemistry 16 2110058
2009 Ribosomal interaction of Bacillus stearothermophilus translation initiation factor IF2: characterization of the active sites. Journal of molecular biology 15 19917289
2003 Characterization of mutations in the GTP-binding domain of IF2 resulting in cold-sensitive growth of Escherichia coli. Journal of molecular biology 15 12559921
2000 Macromolecular mimicry in translation initiation: a model for the initiation factor IF2 on the ribosome. IUBMB life 15 11327306
2024 Methionine-driven YTHDF1 expression facilitates bladder cancer progression by attenuating RIG-I-modulated immune responses and enhancing the eIF5B-PD-L1 axis. Cell death and differentiation 14 39672819
2000 Initiation of protein synthesis with fluorophore-Met-tRNA(f) and the involvement of IF-2. Biochimie 14 10727773
2017 IF2 and unique features of initiator tRNAfMet help establish the translational reading frame. RNA biology 13 28914580
2008 Requirements for translation re-initiation in Escherichia coli: roles of initiator tRNA and initiation factors IF2 and IF3. Molecular microbiology 13 18221266
2007 Molecular genetic structure-function analysis of translation initiation factor eIF5B. Methods in enzymology 13 17913624
2023 IGF2BP3-induced activation of EIF5B contributes to progression of hepatocellular carcinoma cells. Oncology research 12 37305324
2022 In silico analysis reveals the co-existence of CRISPR-Cas type I-F1 and type I-F2 systems and its association with restricted phage invasion in Acinetobacter baumannii. Frontiers in microbiology 12 36060733
2012 GTPases IF2 and EF-G bind GDP and the SRL RNA in a mutually exclusive manner. Scientific reports 11 23150791
1992 Tandem translation of Bacillus subtilis initiation factor IF2 in E. coli. Over-expression of infBB.su in E. coli and purification of alpha- and beta-forms of IF2B.su. FEBS letters 11 1426242
1990 Purified internal G-domain of translational initiation factor IF-2 displays guanine nucleotide binding properties. Biochemistry 11 2125480
1978 Initiation factor IF-3 and the binary complex between initiation factor IF-2 and formylmethionyl-tRNA are mutually exclusive on the 30-S ribosomal subunit. European journal of biochemistry 11 359327
2025 A cohort-based multi-omics identifies nuclear translocation of eIF5B /PD-L1/CD44 complex as the target to overcome Osimertinib resistance of ARID1A-deficient lung adenocarcinoma. Experimental hematology & oncology 10 39773749
2008 Translation initiation factor IF1 of Bacillus stearothermophilus and Thermus thermophilus substitute for Escherichia coli IF1 in vivo and in vitro without a direct IF1-IF2 interaction. Molecular microbiology 10 18976282
1997 Identification and purification of translation initiation factor 2 (IF2) from Thermus thermophilus. European journal of biochemistry 10 9030723
1980 The role of the codon and the initiation factor IF-2 in the selection of N-blocked aminoacyl-tRNA for initiation. European journal of biochemistry 10 6989597
2022 Essential Role for an Isoform of Escherichia coli Translation Initiation Factor IF2 in Repair of Two-Ended DNA Double-Strand Breaks. Journal of bacteriology 9 35343794
2016 Proteomic Analysis of eIF5B Silencing-Modulated Proteostasis. PloS one 9 27959964
2012 Translation initiation without IF2-dependent GTP hydrolysis. Nucleic acids research 9 22723375
2011 Structural transitions of translation initiation factor IF2 upon GDPNP and GDP binding in solution. Biochemistry 9 21988058
1984 The rate of evolutionary divergence of initiation factors IF2 and IF3 in various bacterial species determined quantitatively by immunoblotting. Archives of microbiology 9 6084987
2022 Modulation of RecFORQ- and RecA-Mediated Homologous Recombination in Escherichia coli by Isoforms of Translation Initiation Factor IF2. Journal of bacteriology 8 35343793
2021 eIF5B regulates the expression of PD-L1 in prostate cancer cells by interacting with Wig1. BMC cancer 8 34525951
2020 Depletion of eukaryotic initiation factor 5B (eIF5B) reprograms the cellular transcriptome and leads to activation of endoplasmic reticulum (ER) stress and c-Jun N-terminal kinase (JNK). Cell stress & chaperones 8 33123915
2011 Solubility partner IF2 Domain I enables high yield synthesis of transducible transcription factors in Escherichia coli. Protein expression and purification 8 21757009
1992 Proteolysis of Bacillus stearothermophilus IF2 and specific protection by fMet-tRNA. FEBS letters 8 1544401

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