Affinage

UBE2G2

Ubiquitin-conjugating enzyme E2 G2 · UniProt P60604

Length
165 aa
Mass
18.6 kDa
Annotated
2026-06-10
20 papers in source corpus 17 papers cited in narrative 17 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

UBE2G2 is a class I E2 ubiquitin-conjugating enzyme that builds Lys-48-linked polyubiquitin chains for proteasomal degradation, functioning centrally in ER-associated degradation (ERAD) through cooperation with RING E3 ligases (PMID:9693041, PMID:16582478, PMID:19223579). A defining mechanistic feature is that UBE2G2 preassembles Lys-48-linked polyubiquitin chains on its own catalytic cysteine as active site-linked intermediates prior to substrate transfer; the E3 gp78 oligomerizes and engages multiple UBE2G2 molecules through a surface distinct from the RING-binding site, juxtaposing them so ubiquitin moieties are transferred between neighboring UBE2G2s to elongate the chain (PMID:19223579). Catalysis is governed by conformational dynamics: two dynamic loops flanking the active-site cysteine require binding partners to adopt a catalytically competent state, and E3 engagement shifts the UBE2G2~ubiquitin conjugate into a closed, active conformation that is the rate-limiting step of ligation (PMID:20014027, PMID:28884161). gp78 activates UBE2G2 allosterically through dual contacts, with its G2BR domain increasing RING affinity ~50-fold, after which RING binding triggers G2BR release (PMID:28434917). The G2BR domain of AUP1 binds the backside of UBE2G2 with nanomolar affinity to stabilize the enzyme, recruit it to the ER membrane, and allosterically activate it for ERAD (PMID:21127063, PMID:34879065); backside occupancy differentially tunes UBE2G2 activity across distinct E3 ligases (PMID:40234692). Through these partnerships UBE2G2 ubiquitinates ERAD and other substrates including HERP, proinsulin, LGALS3BP (with TRIM38), and ACSL4 (PMID:24496447, PMID:39807310, PMID:38787820, PMID:41125048). Beyond degradation, the AUP1-UBE2G2 complex retains STING at the ER to suppress type I interferon signaling (PMID:40237449), and the cytosolic pool of UBE2G2 regulates cell shape, actin organization, and motility (PMID:41989348).

Mechanistic history

Synthesis pass · year-by-year structured walk · 12 steps
  1. 1998 Medium

    Establishing UBE2G2 as the human ortholog of yeast Ubc7p placed it within the ubiquitin-conjugating enzyme family linked to proteasomal degradation, defining the gene to study.

    Evidence cDNA cloning, sequence analysis, and chromosomal mapping

    PMID:9693041

    Open questions at the time
    • No enzymatic activity demonstrated directly
    • No substrates or E3 partners identified
  2. 2006 High

    Solving the crystal structure confirmed UBE2G2 as a class I E2 fold and identified loop regions for RING engagement, providing a structural framework for E3 interactions.

    Evidence X-ray crystallography at 2.56 Å with comparison to Ubc7 and UbcH7

    PMID:16582478

    Open questions at the time
    • Static structure does not capture catalytic dynamics
    • No bound E3 or ubiquitin in the structure
  3. 2009 High

    Resolving how gp78 oligomers engage multiple UBE2G2 molecules explained how Lys-48 chains are preassembled on the catalytic cysteine before substrate transfer, a non-canonical chain-building mechanism.

    Evidence Biochemical oligomerization assays, mutagenesis, and in vitro ubiquitination reconstitution

    PMID:19223579

    Open questions at the time
    • Stoichiometry and dynamics of chain elongation in vivo unresolved
    • Whether other E3s use the same juxtaposition mechanism unknown
  4. 2010 High

    NMR dynamics and ubiquitin-binding studies showed that active-site loops and ubiquitin recognition require partner binding to reach a catalytic conformation and revealed Lys-48 chain positioning preferences, defining the conformational logic of catalysis.

    Evidence NMR spin relaxation, residual dipolar coupling, chemical shift perturbation, and computational docking

    PMID:20014027 PMID:21098018

    Open questions at the time
    • Direct functional validation of His94 as general base limited to mutagenesis rationale
    • Ubiquitin binding measured in isolation, not in full E2-E3 context
  5. 2010 High

    Identifying AUP1 as a G2BR-domain partner that binds UBE2G2 at lipid droplets connected the ubiquitination machinery to a membrane compartment via a defined recruitment domain.

    Evidence Co-immunoprecipitation, domain mutagenesis, fluorescence microscopy, and fractionation

    PMID:21127063

    Open questions at the time
    • Functional consequence of lipid-droplet localization for substrates not defined here
    • Whether G2BR also activates UBE2G2 not addressed in this study
  6. 2014 High

    Demonstrating gp78-UBE2G2 polyubiquitylation of HERP via gp78 CUE–HERP UBL contacts identified a specific ERAD substrate and mapped the recruitment interface, linking the enzyme to ER stress recovery.

    Evidence In vitro ubiquitylation, co-IP, domain mapping, and cell-based degradation assays

    PMID:24496447

    Open questions at the time
    • Generalizability of CUE-UBL substrate recruitment to other substrates unclear
    • Chain topology on HERP not directly characterized
  7. 2017 High

    Quantifying gp78 G2BR/RING allostery and the conformational shift to the closed active state established how E3 binding accelerates catalysis and identified active-site organization as rate-limiting.

    Evidence NMR conformational dynamics, binding affinity measurements, and single-turnover diubiquitin assays

    PMID:28434917 PMID:28884161

    Open questions at the time
    • Sequence of allosteric events inferred from NMR populations, not real-time kinetics
    • How allostery integrates with multi-E2 chain assembly unresolved
  8. 2021 High

    Structural and functional dissection of the AUP1 G2BR–UBE2G2 interface showed that AUP1 binding stabilizes UBE2G2, recruits it to the ER, and allosterically activates it for ERAD, defining AUP1 as a key activating partner.

    Evidence Structural analysis, co-IP, in vitro ubiquitination, cell-based ERAD assays, and mutagenesis

    PMID:34879065

    Open questions at the time
    • Substrate range stabilized by AUP1-bound UBE2G2 not enumerated
    • Interplay between AUP1 and gp78 backside binding not resolved
  9. 2024 Medium

    Identifying UBE2G2 in degradation of proinsulin and in LGALS3BP ubiquitination (with TRIM38) extended its substrate repertoire beyond canonical ERAD into antigen generation and tumor signaling control.

    Evidence E2 knockdown screening, ERAD/antigen presentation assays, co-IP, and site-directed ubiquitination mapping (K104)

    PMID:38787820 PMID:39807310

    Open questions at the time
    • Single-lab studies for each substrate
    • Direct E3 pairing for proinsulin ERAD not defined
  10. 2025 Medium

    Discovery that the AUP1-UBE2G2 complex retains STING at the ER, and that backside occupancy differentially tunes activity across HRD1/CHIP/TRC8, expanded UBE2G2 into innate immune regulation and revealed E3-selective control via its backside surface.

    Evidence Co-IP, genetic loss-of-function, STING signaling and viral infection models; nanobody and multi-E3 in vitro ubiquitination

    PMID:40234692 PMID:40237449

    Open questions at the time
    • Whether STING retention requires catalytic activity not fully resolved
    • Backside-driven E3 selectivity tested in vitro only
  11. 2025 Medium

    Linking m6A-dependent YTHDF3 control of UBE2G2 mRNA stability to ACSL4 ubiquitination connected enzyme abundance to lipid peroxidation and ferroptosis, a degradation-dependent cell-fate axis.

    Evidence RIP-qPCR, MeRIP-qPCR, expression manipulation, and in vitro ubiquitination

    PMID:41125048

    Open questions at the time
    • E3 ligase for ACSL4 ubiquitination not identified
    • Single-lab correlative axis
  12. 2026 Medium

    Showing that catalytically dead UBE2G2 and AUP1-mediated sequestration alter actin organization and motility established a cytosolic, cell-shape-regulating role distinct from membrane ERAD.

    Evidence Inactive mutant expression, live-cell imaging, actin/vinculin staining, wound healing, and membrane sequestration

    PMID:41989348

    Open questions at the time
    • Cytoskeletal substrates of UBE2G2 not identified
    • Mechanism linking ubiquitination to actin remodeling unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • How UBE2G2 substrate selection is partitioned across its multiple E3 partners and how its non-ERAD functions (STING retention, cytoskeletal regulation) mechanistically couple to chain assembly remain open.
  • No unifying rule for E3/substrate selectivity
  • Cytoskeletal and immune roles lack defined substrate or chain-type assignment

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140096 catalytic activity, acting on a protein 4 GO:0016740 transferase activity 3 GO:0031386 protein tag activity 2
Localization
GO:0005783 endoplasmic reticulum 2 GO:0005811 lipid droplet 1 GO:0005829 cytosol 1
Pathway
R-HSA-392499 Metabolism of proteins 3 R-HSA-8953897 Cellular responses to stimuli 2 R-HSA-168256 Immune System 1
Complex memberships
AUP1-UBE2G2 complexgp78-UBE2G2 complex

Evidence

Reading pass · 17 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1998 UBE2G2 was identified as the human homologue of yeast Ubc7p, confirmed to be ubiquitously expressed, and mapped to chromosome 21q22.3. It encodes a 165-amino-acid protein with significant similarity to other UBC family members involved in proteasome-dependent degradation. cDNA cloning, sequence analysis, chromosomal mapping Genomics Medium 9693041
2005 Recombinant His-tagged UBE2G2 expressed in E. coli adopts the typical alpha/beta secondary structure of class I E2 enzymes and is enzymatically active, capable of binding ubiquitin molecules when exposed to HeLa cell extract in an in vitro ubiquitin-binding assay. Recombinant protein expression, nickel-affinity purification, circular dichroism, in vitro ubiquitin-binding assay Protein expression and purification Medium 16214370
2006 Crystal structure of human UBE2G2 solved at 2.56 Å resolution; the structure comprises an antiparallel beta-sheet with four strands, five alpha-helices, and two 3(10)-helices. Structural comparison with yeast Ubc7 and UbcH7 suggested that two loop regions of UBE2G2 interact with RING domains, with an extra loop potentially conferring binding specificity. X-ray crystallography Acta crystallographica. Section F High 16582478
2009 gp78 forms oligomers via a hydrophobic segment in its cytosolic domain; a gp78 oligomer can simultaneously associate with multiple Ube2g2 molecules via a novel Ube2g2 surface distinct from the predicted RING binding site. This heterooligomeric assembly brings multiple Ube2g2 molecules into proximity, enabling transfer of ubiquitin moieties between neighboring Ube2g2s to form Lys-48-linked active site-linked polyubiquitin chains on the Ube2g2 catalytic cysteine prior to substrate transfer. Biochemical oligomerization assays, site-directed mutagenesis, in vitro ubiquitination assays Proceedings of the National Academy of Sciences of the United States of America High 19223579
2010 Solution NMR structure of Ube2g2 revealed that two catalytically important loops flanking the active site cysteine (residues 95-107 and 130-135) are highly dynamic. 15N spin relaxation and residual dipolar coupling analysis showed these loops require binding partners (E3, acceptor ubiquitin, or thiolester-linked donor ubiquitin) to adopt a catalytically relevant conformation. His94 was identified as a potential general base activated by carboxylate side-chains of Asp98 or Asp99. NMR spectroscopy, 15N spin relaxation, residual dipolar coupling analysis Proteins High 20014027
2010 AUP1 localizes to lipid droplets in a monotopic fashion with both termini facing the cytosol, and binds Ube2g2 via its C-terminal G2BR domain. Deletion or mutation of the G2BR domain abolishes Ube2g2 binding without affecting AUP1's LD localization. The AUP1-Ube2g2 complex at lipid droplets provides a direct molecular link between lipid droplets and the cellular ubiquitination machinery. Co-immunoprecipitation, domain deletion/mutation analysis, fluorescence microscopy, subcellular fractionation The Journal of biological chemistry High 21127063
2010 Ube2g2 binds ubiquitin with ~90 μM affinity in two orientations rotated 180°. It binds Lys-48-linked and Lys-63-linked diubiquitin primarily through the distal ubiquitin subunit (containing the free Lys-48 or Lys-63). For Lys-48-linked diubiquitin, there is ~3-fold preference for the distal subunit, attributed to partial steric occlusion of the proximal subunit's Lys-48, suggesting Lys-48-linked chains are designed to position the terminal ubiquitin's reactive Lys-48 for chain elongation. NMR chemical shift perturbation, paramagnetic relaxation enhancement, RosettaDock computational modeling The Journal of biological chemistry Medium 21098018
2014 Ube2g2 in complex with E3 ligase gp78 mediates polyubiquitylation of HERP, targeting it for proteasomal degradation during ER stress recovery. The polyubiquitylation of HERP in vitro depends on a physical interaction between the CUE domain of gp78 and the ubiquitin-like (UBL) domain of HERP, and this interaction is essential for HERP degradation in vivo. In vitro ubiquitylation assay, co-immunoprecipitation, domain mapping, cell-based degradation assays Journal of cell science High 24496447
2017 NMR conformational dynamics analysis showed that the G2BR domain of gp78 increases the affinity between the RING domain and Ube2g2 by 50-fold via allostery. Binding of G2BR and RING to two distant regions of Ube2g2 sequentially progresses toward ubiquitin transfer through redistribution of ground and excited conformational state populations. The RING domain binding triggers departure of G2BR in an allosteric fashion. NMR spectroscopy, conformational dynamics analysis, binding affinity measurements Structure High 28434917
2017 gp78 RING domain binding to Ube2g2 increases the population of the closed (catalytically active) conformation of Ube2g2~Ub conjugates from ~60% to ~82%. Mutations in the hydrophobic patch of the thiolester-linked ubiquitin that abolish closed conformation also abolish catalytic activity. Organization of the active site into a catalytically viable conformation is the rate-limiting step for a single ubiquitin ligation event. NMR spectroscopy, single-turnover diubiquitin formation assays, site-directed mutagenesis ACS omega High 28884161
2021 The 27-amino acid G2BR domain of AUP1 binds with high specificity and low nanomolar affinity to the backside of UBE2G2. Crystal/structural analysis of the AUP1 G2BR-UBE2G2 complex revealed an interface with salt bridges, hydrogen bonds, and hydrophobic interactions. G2BRAUP1 allosterically activates UBE2G2-mediated ubiquitination in vitro. In cells, AUP1 G2BR binding prevents rapid degradation of UBE2G2, recruits UBE2G2 to the ER membrane, and is required for UBE2G2 activation at the ER membrane for ERAD. Co-immunoprecipitation, structural analysis, in vitro ubiquitination assay, cell-based ERAD assays, site-directed mutagenesis, fluorescence microscopy PLoS biology High 34879065
2024 UBE2G2 directly binds to LGALS3BP and forms a complex with E3 ubiquitin ligase TRIM38, facilitating ubiquitination-mediated degradation of LGALS3BP at the K104 residue. This suppresses PI3K/AKT signaling and inhibits vasculogenic mimicry and metastasis in uveal melanoma. Co-immunoprecipitation, ubiquitination assays, site-directed mutagenesis (K104 site identification), knockdown/overexpression with phenotypic readouts Acta pharmaceutica Sinica. B Medium 39807310
2024 UBE2G2 is required for ERAD-mediated degradation of proinsulin and is involved in the generation of the proinsulin B-chain autoantigen PPIB10-18. Screening of E2 ubiquitin conjugating enzymes identified UBE2G2 as specifically involved in this process. Gene knockdown screening of E2 enzymes, cell-based ERAD and antigen presentation assays PloS one Medium 38787820
2025 AUP1 forms a complex with UBE2G2 that interacts with STING, retaining STING in the ER membrane and preventing its translocation to the Golgi and subsequent signaling. Deficiency of either AUP1 or UBE2G2 causes spontaneous STING activation and enhanced type I interferon expression, demonstrating that the AUP1-UBE2G2 complex is a negative regulator of STING-dependent innate immune signaling. Co-immunoprecipitation, genetic knockdown/knockout, cell-based STING signaling assays, in vitro and in vivo viral infection models mBio Medium 40237449
2025 A nanobody binding to the backside region of Ube2G2 does not affect ubiquitin loading but differentially inhibits E3-mediated ubiquitination, with order of inhibition HRD1 > CHIP >> TRC8. Occupation of the backside site on Ube2G2 thus differentially affects its interactions with different E3 ligases. G2BR of gp78 enhances Ube2G2 activity when present in cis but its deletion results in similar inhibition as the nanobody. Nanobody binding assay, in vitro ubiquitination assays with multiple E3 ligases Communications biology Medium 40234692
2025 The m6A reader YTHDF3 directly binds UBE2G2 mRNA in an m6A-dependent manner (confirmed by RIP-qPCR and MeRIP-qPCR), and controls UBE2G2 mRNA stability. Reduced UBE2G2 expression impairs ubiquitination of ACSL4, resulting in ACSL4 stabilization, lipid peroxidation, and ferroptosis. RIP-qPCR, MeRIP-qPCR, gene overexpression/knockdown, in vitro ubiquitination assay Ecotoxicology and environmental safety Medium 41125048
2026 Inactive (catalytically dead) UBE2G2 induces cell elongation independent of matrix properties, reduces actin stress fibers with dominant cortical ventral fibers aligned along the long axis, redistributes vinculin to ventral stress fibers, and impairs lamellipodia formation. Sequestration of wild-type UBE2G2 by AUP1 to the membrane fraction mimics the elongated phenotype, demonstrating that the cytosolic pool of UBE2G2 is responsible for regulating cell shape and motility. Inactive mutant expression, live-cell imaging, actin/vinculin immunostaining, wound healing assay, AUP1-mediated membrane sequestration FASEB journal Medium 41989348

Source papers

Stage 0 corpus · 20 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2010 Ancient ubiquitous protein 1 (AUP1) localizes to lipid droplets and binds the E2 ubiquitin conjugase G2 (Ube2g2) via its G2 binding region. The Journal of biological chemistry 105 21127063
2009 Mechanistic insights into active site-associated polyubiquitination by the ubiquitin-conjugating enzyme Ube2g2. Proceedings of the National Academy of Sciences of the United States of America 83 19223579
2014 Ube2g2-gp78-mediated HERP polyubiquitylation is involved in ER stress recovery. Journal of cell science 37 24496447
2010 Solution structure and dynamics of human ubiquitin conjugating enzyme Ube2g2. Proteins 29 20014027
2017 Conformational Dynamics and Allostery in E2:E3 Interactions Drive Ubiquitination: gp78 and Ube2g2. Structure (London, England : 1993) 26 28434917
1998 Identification, expression, and chromosomal localization of ubiquitin conjugating enzyme 7 (UBE2G2), a human homologue of the Saccharomyces cerevisiae ubc7 gene. Genomics 26 9693041
2006 Structure of human ubiquitin-conjugating enzyme E2 G2 (UBE2G2/UBC7). Acta crystallographica. Section F, Structural biology and crystallization communications 20 16582478
2010 Mechanism of polyubiquitin chain recognition by the human ubiquitin conjugating enzyme Ube2g2. The Journal of biological chemistry 16 21098018
2021 A structurally conserved site in AUP1 binds the E2 enzyme UBE2G2 and is essential for ER-associated degradation. PLoS biology 14 34879065
2018 Ubc7/Ube2g2 ortholog in Entamoeba histolytica: connection with the plasma membrane and phagocytosis. Parasitology research 10 29594345
2018 Design, synthesis, and anticancer activity evaluation of irreversible allosteric inhibitors of the ubiquitin-conjugating enzyme Ube2g2. MedChemComm 7 30542531
2024 UBE2G2 inhibits vasculogenic mimicry and metastasis of uveal melanoma by promoting ubiquitination of LGALS3BP. Acta pharmaceutica Sinica. B 6 39807310
2024 Proinsulin degradation and presentation of a proinsulin B-chain autoantigen involves ER-associated protein degradation (ERAD)-enzyme UBE2G2. PloS one 5 38787820
2017 Conformational Dynamics Modulate Activation of the Ubiquitin Conjugating Enzyme Ube2g2. ACS omega 5 28884161
2005 Expression, purification, and structural analysis of (HIS)UBE2G2 (human ubiquitin-conjugating enzyme). Protein expression and purification 5 16214370
2022 The Protective Effect of UBE2G2 Knockdown Against Atherosclerosis in Apolipoprotein E-Deficient Mice and Its Association with miR-204-5p. Molecular biotechnology 2 35394254
2025 A nanobody that binds to the backside of the ubiquitin conjugating enzyme Ube2G2 differentially affects interactions with its partner E3 Ligases. Communications biology 1 40234692
2025 AUP1 and UBE2G2 complex targets STING signaling and regulates virus-induced innate immunity. mBio 1 40237449
2025 RNA m6A reader YTHDF3/ UBE2G2 m6A methylation/ ACSL4 ubiquitination axis facilitated cell ferroptosis to mediate benzene hematotoxicity and the protective effect of melatonin. Ecotoxicology and environmental safety 1 41125048
2026 A Novel Role of the Ubiquitin Conjugating Enzyme, UBE2G2, in Regulation of Cell Shape and Movement. FASEB journal : official publication of the Federation of American Societies for Experimental Biology 0 41989348

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