Affinage

CDC34

Ubiquitin-conjugating enzyme E2 R1 · UniProt P49427

Length
236 aa
Mass
26.7 kDa
Annotated
2026-04-28
82 papers in source corpus 44 papers cited in narrative 43 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

CDC34 (Ube2R1) is a ubiquitin-conjugating enzyme (E2) that functions as the dedicated E2 partner of SCF (Skp1–Cullin–F-box) cullin-RING E3 ligase complexes to drive Lys48-linked polyubiquitination and proteasomal degradation of cell-cycle regulators and signaling proteins, thereby controlling the G1/S transition, S-phase entry, and mitotic timing (PMID:2842867, PMID:9285816, PMID:9836638). CDC34 catalyzes ubiquitin transfer in two mechanistically distinct steps—rate-limiting attachment of the first ubiquitin to substrate, followed by rapid processive K48-linked chain elongation—with the conserved acidic loop conferring linkage specificity and processivity, and an intrinsically disordered acidic C-terminal tail mediating electrostatic docking to the SCF basic canyon and intramolecular contact with the thioester-linked ubiquitin to orient chain assembly (PMID:16360039, PMID:19875449, PMID:21296085). CK2 phosphorylation of both the catalytic domain (S130, S167) and the C-terminal tail stimulates ubiquitin charging and SCF-dependent ubiquitination activity, coupling CDC34 function to proliferative signaling (PMID:11546811, PMID:18418079). Through partnership with distinct F-box substrate receptors, CDC34/SCF targets Sic1, p27, Wee1, Swe1, IκBα, Met4, and other substrates for ubiquitin-dependent regulation, and a selective allosteric inhibitor (CC0651) blocks ubiquitin discharge and stabilizes p27 in cells (PMID:10385629, PMID:21683433).

Mechanistic history

Synthesis pass · year-by-year structured walk · 17 steps
  1. 1988 High

    Established that CDC34 encodes a ubiquitin-conjugating enzyme required for the G1/S transition, answering the fundamental question of what biochemical activity underlies CDC34 cell-cycle function.

    Evidence Bacterially expressed Cdc34 catalyzed ubiquitin attachment to histones in vitro; sequence homology to RAD6 E2

    PMID:2842867

    Open questions at the time
    • Physiological substrates unknown
    • No E3 ligase partner identified
    • Mechanism of cell cycle arrest not defined
  2. 1991 High

    Demonstrated that Cdc34 preferentially assembles K48-linked polyubiquitin chains processively, distinguishing its linkage specificity from other E2s like RAD6.

    Evidence In vitro conjugation assays with wild-type and K48R ubiquitin variants; kinetic analysis

    PMID:1848239

    Open questions at the time
    • Structural basis for K48 specificity unknown
    • No physiological substrate tested
  3. 1992 High

    Revealed that the unique 125-residue C-terminal tail is a portable functional determinant sufficient to confer CDC34 cell-cycle activity when grafted onto RAD6, separating catalytic core from regulatory tail functions.

    Evidence Chimeric E2 constructs complementing cdc34 and rad6 mutants in yeast

    PMID:1639075 PMID:1639076

    Open questions at the time
    • Biochemical role of the tail (binding vs. catalysis) not resolved
    • Tail binding partners unidentified
  4. 1994 High

    Identified Cdc34 self-association (dimerization) mediated by the C-terminal tail as a requirement for cell-cycle function, raising the question of whether oligomerization activates chain assembly.

    Evidence Chemical cross-linking and in vivo complementation of cdc34 mutants with tail deletions

    PMID:7929378

    Open questions at the time
    • Whether dimerization is required for catalysis or SCF recruitment unclear
    • Stoichiometry at SCF not determined
  5. 1997 High

    Connected CDC34 to its first well-defined physiological substrate: Sic1 degradation requires Cdc34 and Cdc4, with phosphorylation by Cln/Cdc28 kinases triggering ubiquitination of the Sic1 N-terminus.

    Evidence In vitro reconstitution with DEAE-fractionated yeast extracts and cdc4-ts mutant extracts

    PMID:9285816

    Open questions at the time
    • SCF complex composition not fully defined
    • Mechanism of phosphodegron recognition unclear
  6. 1998 High

    Defined the SCF architecture: Cdc53 scaffolds independent binding sites for Cdc34 and Skp1, and Skp1 bridges to F-box proteins (Cdc4, Met30, Grr1), establishing the modular E3 complex through which Cdc34 targets multiple substrates including Swe1.

    Evidence Reciprocal co-IP, two-hybrid, and genetic epistasis in yeast; Swe1 ubiquitination assays with mutant extracts

    PMID:9499404 PMID:9716410

    Open questions at the time
    • RING subunit not yet identified
    • How Cdc34 is recruited to cullin not structurally resolved
  7. 1999 High

    Identified the RING protein Hrt1/Rbx1 as a critical SCF subunit that directly binds Cdc34 and stimulates E3 activity, completing the four-subunit SCF model and enabling full reconstitution of substrate ubiquitination.

    Evidence Mass spectrometry identification of Hrt1; recombinant reconstitution of Cln2 ubiquitination

    PMID:10385629

    Open questions at the time
    • Structural basis of RING-Cdc34 interaction unknown
    • Whether RING activates Cdc34 allosterically or by proximity not resolved
  8. 2000 High

    Expanded the functional repertoire of Cdc34/SCF to include non-proteolytic ubiquitination: SCF(Met30)-mediated ubiquitination of Met4 represses transcription without triggering degradation, and Cdc34/SCF(βTrCP) catalyzes phosphorylation-dependent ubiquitination of IκBα.

    Evidence ChIP and metabolic labeling showing stable ubiquitinated Met4 at promoters; reconstitution of IκBα ubiquitination with recombinant components

    PMID:10918611 PMID:10975521

    Open questions at the time
    • Mechanism distinguishing proteolytic from non-proteolytic ubiquitination unclear
    • Chain length determinants for proteasomal targeting unknown
  9. 2001 High

    Identified CK2 as the kinase phosphorylating CDC34 at five C-terminal sites, with phosphorylation controlling nuclear localization and linking proliferative signaling to E2 regulation.

    Evidence Yeast two-hybrid, co-IP with CK2β, in vitro kinase assay, phosphosite mutagenesis altering nuclear localization

    PMID:11546811

    Open questions at the time
    • Whether phosphorylation affects catalytic activity not yet tested
    • Phosphorylation dynamics during cell cycle unknown
  10. 2003 High

    Demonstrated that ubiquitin charging triggers release of Cdc34 from the SCF RING domain, and that this dissociation is essential for substrate ubiquitination—explaining why Cdc34 must cycle on and off SCF during multisite ubiquitination.

    Evidence Kinetic binding measurements and F72V Cdc34 mutant with increased RING affinity that fails to ubiquitinate Sic1

    PMID:13678584

    Open questions at the time
    • How released Cdc34~Ub reaches the substrate lysine not visualized
    • Whether multiple Cdc34 molecules act simultaneously unclear
  11. 2005 High

    Separated Cdc34 catalysis into two kinetically distinct steps—slow first-ubiquitin attachment and rapid processive chain elongation—and identified the acidic loop as selectively required for processivity and K48-linkage specificity during elongation.

    Evidence In vitro reconstitution with purified recombinant SCF(Cdc4)/Cdc34; acidic loop mutagenesis; kinetic analysis

    PMID:16360039

    Open questions at the time
    • Structural basis for how the acidic loop orients acceptor ubiquitin not determined
    • Whether the two-step model applies to all SCF substrates unclear
  12. 2007 High

    Mapped distinct catalytic determinants for monoubiquitination versus polyubiquitination on Cdc34, and showed that CK2 phosphorylation of the C-terminal tail stimulates SCF-dependent ubiquitination activity in vitro and cell-cycle progression in vivo.

    Evidence Systematic mutagenesis of Cdc34 catalytic core and charged stretch with IκBα reconstitution; CK2 phosphorylation of tail sites and Sic1 ubiquitination assays; yeast cell-cycle synchronization

    PMID:17461777 PMID:17698585

    Open questions at the time
    • Whether tail phosphorylation affects SCF binding affinity not quantified
    • Structural model of phosphorylated tail at SCF lacking
  13. 2008 High

    Extended CK2 regulation to the Cdc34 catalytic domain itself: phosphorylation at S130/S167 stimulates ubiquitin charging (E1→E2 transfer), and these sites are essential for cell viability.

    Evidence MS-confirmed phosphosites; ubiquitin-charging assay; complementation of cdc34-2ts yeast

    PMID:18418079

    Open questions at the time
    • Structural mechanism by which catalytic-domain phosphorylation enhances charging unknown
    • Interplay between tail and core phosphorylation not dissected
  14. 2009 High

    Demonstrated that the acidic C-terminal tail contributes both sub-micromolar SCF binding affinity and catalytic function through its net negative charge, with the tail contacting the SCF basic canyon—and that let-7 miRNA post-transcriptionally regulates CDC34 levels to control Wee1 stability and G2/M progression.

    Evidence Binding affinity measurements and tail charge mutants; Cdc34-Cul1 fusion proteins; let-7 3′-UTR reporter assays and Wee1 epistasis by siRNA

    PMID:19126550 PMID:19875449

    Open questions at the time
    • Atomic resolution structure of tail–canyon interaction not available
    • Physiological significance of let-7 regulation in vivo not confirmed in animal models
  15. 2010 High

    Revealed a two-E2 relay for IκBα ubiquitination—UbcH5 primes monoubiquitination, then Cdc34 elongates K48-linked chains—and mapped two non-covalent ubiquitin-binding sites in the Cdc34 C-terminus by NMR, with Y210 required for donor ubiquitin transfer.

    Evidence Reconstitution with UbcH5 and Cdc34 on IκBα; NMR chemical shift perturbation mapping of UBS1/UBS2; mutagenesis

    PMID:20347421 PMID:20353940

    Open questions at the time
    • Whether two-E2 relay is general for all SCF substrates unknown
    • How UBS sites coordinate with acidic loop during chain elongation not structurally resolved
  16. 2011 High

    Provided structural and pharmacological insights: NMR showed the disordered C-terminus contacts thioester-bound ubiquitin in a closed conformation directing K48 specificity; ubiquitin I44 promotes acceptor lysine deprotonation; and the allosteric inhibitor CC0651 blocks ubiquitin discharge from a cryptic pocket, stabilizing p27 in cells.

    Evidence NMR of Cdc34~Ub disulfide mimetic; compensatory mutagenesis with pH-dependence; crystal structure of Cdc34-CC0651 complex; cell-based p27 accumulation

    PMID:21296085 PMID:21474069 PMID:21683433

    Open questions at the time
    • CC0651 selectivity mechanism across E2 family not fully explained
    • Full closed-state structure of Cdc34~Ub at SCF not determined
  17. 2019 High

    Crystal structures of Cdc34 alone, with E1, and as a Ub thioester mimetic revealed a unique E1-binding mode requiring conformational changes in both enzymes for transthiolation, and confirmed the C-terminal extension stabilizes a closed conformation critical for ubiquitin discharge.

    Evidence X-ray crystallography of three Cdc34 states; mutagenesis; cell-based assays

    PMID:31341161

    Open questions at the time
    • No structure of Cdc34 bound to an intact SCF-substrate complex
    • Dynamics of conformational switching during catalytic cycle not captured

Open questions

Synthesis pass · forward-looking unresolved questions
  • A complete structural view of Cdc34 engaged with an SCF-substrate complex during catalysis, the mechanistic basis for how CK2 phosphorylation at both core and tail sites coordinately regulate activity, and the generality of the two-E2 priming/elongation relay across SCF substrates remain open questions.
  • No cryo-EM or crystal structure of Cdc34~Ub bound to SCF with substrate
  • Relative contributions of core vs. tail CK2 phosphorylation not quantitatively dissected in vivo
  • Whether two-E2 relay (UbcH5 priming → Cdc34 elongation) applies to substrates beyond IκBα not established

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140096 catalytic activity, acting on a protein 6 GO:0016740 transferase activity 4
Localization
GO:0005634 nucleus 3 GO:0005829 cytosol 1
Pathway
R-HSA-392499 Metabolism of proteins 5 R-HSA-1640170 Cell Cycle 4 R-HSA-162582 Signal Transduction 2 R-HSA-168256 Immune System 1
Partners
BTRCCDC4CSNK2BCUL1MET30RBX1SKP1
Complex memberships
SCF (Skp1-Cul1-F-box-Rbx1)

Evidence

Reading pass · 43 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1988 CDC34 encodes a ubiquitin-conjugating enzyme (E2) required for the G1-to-S phase transition; the bacterially expressed product catalyzes covalent attachment of ubiquitin to histones H2A and H2B in vitro, demonstrating E2 activity. In vitro ubiquitination assay with bacterially expressed protein; sequence homology to RAD6 Science High 2842867
1991 Cdc34 (and its rabbit homolog E2(32K)) preferentially catalyze processive multiubiquitination via Lys-48 of ubiquitin, distinguishing them from RAD6/E2(20K) which use non-Lys48 linkages; Cdc34 shows specificity for BSA rather than core histones. In vitro ubiquitin conjugation assay with native, reductively methylated, and K48R ubiquitin variants; kinetic analysis The Journal of biological chemistry High 1848239
1992 The 125-residue C-terminal tail of Cdc34 (specifically residues 171–244) is a portable determinant of cell cycle function; transplanting this tail onto the RAD6 catalytic domain creates a chimeric E2 that performs both CDC34 and RAD6 functions in vivo. Chimeric E2 constructs expressed in yeast; in vivo complementation of cdc34 and rad6 mutants; deletion analysis The EMBO journal High 1639075 1639076
1993 Bacterially expressed Cdc34 catalyzes its own ubiquitination (autoubiquitination) via intramolecular transfer forming predominantly a single Lys48-linked multiubiquitin chain, with major linkage sites mapping to C-terminal lysines (K273, K277, K293, K294). In vitro autoubiquitination assay; hydroxylamine cleavage; site-directed mutagenesis of C-terminal lysines The Journal of biological chemistry High 8383676
1994 The Cdc34 C-terminal tail (39 residues adjacent to the catalytic domain) mediates Cdc34 self-association (dimerization) in vitro and in vivo, and this self-association is required for cell cycle function. Chemical cross-linking; biophysical analysis; in vivo phenotypic analysis of CDC34 derivatives in cdc34 mutant strains The Journal of biological chemistry High 7929378
1994 Cdc34 (Ubc3) is itself a substrate for both ubiquitination and phosphorylation in vivo; immunochemical localization places it in the nucleus, suggesting nuclear substrates. In vivo labeling; immunochemical localization Molecular and cellular biology Medium 8164658
1995 Genetic and biochemical evidence demonstrates a noncovalent ubiquitin-binding site on Cdc34; overexpression of ubiquitin suppresses cdc34 temperature-sensitive alleles in an allele-specific manner, and chemical cross-linking confirms a specific noncovalent Ub-Cdc34 interaction. Genetic suppression screen; chemical cross-linking; in vivo ubiquitin overexpression The Journal of biological chemistry Medium 7721857
1995 Dual mutation of CDC34 active-site cysteine (C95S) and conserved Leu99 (L99S) generates a dominant-negative Cdc34 that blocks cell growth and inhibits in vitro ubiquitination of the Cdc34 substrate Cln2. Site-directed mutagenesis; in vitro ubiquitination assay; overexpression growth assay in yeast The Journal of biological chemistry High 7592826
1995 Kinetochore protein Cbf2p (Ndc10p) is ubiquitinated in vivo by Cdc34; purified Cdc34 catalyzes Cbf2p-monoubiquitin conjugate formation in vitro; overexpression of CDC34 suppresses the ndc10-1 temperature-sensitive mutation. In vitro ubiquitination assay with purified proteins; in vivo anti-ubiquitin immunoprecipitation; genetic suppression Molecular and cellular biology Medium 7651401
1997 Multiubiquitination of Sic1 requires cyclin/Cdc28 protein kinase activity, the Cdc34 E2, and Cdc4; the N-terminal 160 residues of Sic1 are necessary and sufficient for Cdc34-dependent ubiquitination. In vitro reconstitution with DEAE-fractionated yeast extracts; cdc4ts mutant extracts; SIC1 deletion analysis Molecular biology of the cell High 9285816
1997 Cdc34 is required for initiation of DNA replication in Xenopus egg extracts; Cdc34p in a large molecular size complex regulates initiation function of Cdk2-cyclin E, likely through degradation of the Xenopus CDK inhibitor Xic1. Xenopus egg extract depletion/add-back experiments; sizing column fractionation Science Medium 9287222
1998 Cdc53 functions as a scaffold protein within the SCF E3 complex, containing independent binding sites for Cdc34 and Skp1; Skp1 bridges Cdc53 to three F-box proteins (Cdc4, Met30, Grr1), conferring substrate specificity on a common Cdc34-Cdc53-Skp1 E2/E3 core. In vivo co-immunoprecipitation; two-hybrid; genetic epistasis Genes & development High 9499404
1998 Cdc34 and the F-box protein Met30 are required for degradation of the Cdk-inhibitory kinase Swe1; Met30 physically binds Swe1 in vivo and extracts from cdc34 or met30 mutants fail to polyubiquitinate Swe1. GST pull-down; in vitro ubiquitination assay with mutant extracts; genetic interaction screen Genes & development High 9716410
1998 Human CDC34 associates in vivo with CUL-1 and the F-box protein p45(SKP2) as part of an SCF-type E3 ubiquitin ligase complex, establishing conservation of the SCF pathway in human cells. Co-immunoprecipitation in vivo from human cells The EMBO journal Medium 9430629
1998 Cdc34-mediated degradation of Wee1 kinase in Xenopus egg extracts is required for timely entry into mitosis; this proteolysis is inhibited when DNA replication is blocked, linking the DNA replication checkpoint to Wee1 stability. Xenopus egg extract biochemical assay; Cdc34 immunodepletion; DNA replication block Science High 9836638
1999 The RING-H2 protein Hrt1 (Rbx1/Roc1) is a subunit of SCF identified by mass spectrometry; it binds Cdc34 directly, stimulates SCF E3 activity, and enables reconstitution of Cln2 ubiquitination; SCF and Cdc53/Hrt1 activate Cdc34 autoubiquitination by a mechanism independent of reactive thiols. Mass spectrometry; recombinant protein reconstitution; in vitro ubiquitination assay; conditional genetic inactivation Genes & development High 10385629
1999 Human Cdc34 ubiquitinates the transcription factor repressors hICERIIγ and hATF5 in mammalian cells; both hCdc34- and hRad6B-dependent ubiquitin-mediated proteolysis abrogates their transcriptional repression of cAMP-induced genes. Transfection assay; dominant-negative and antisense Cdc34 constructs; ubiquitination assay in mammalian cells Molecular and cellular biology Medium 10373550
2000 Cdc34/SCF(Met30) ubiquitinates the transcription factor Met4, causing transcriptional repression without proteolysis; ubiquitinated Met4 associates with target promoters but fails to form functional transcription complexes; deletion of MET4 suppresses lethality of met30 mutants. Genetic epistasis (MET4 deletion suppression); chromatin immunoprecipitation; metabolic labeling to assess Met4 stability Cell High 10975521
2000 SCFβ-TRCP together with Cdc34 (Ubc3) catalyzes phosphorylation-dependent ubiquitination of IκBα; Ubc4 is also capable but is ~19-fold more efficient in THP.1 cells; Cdc34 associates with SCFβ-TRCP isolated from human cells. In vitro reconstitution with recombinant components; ubiquitination assay; pull-down of Cdc34 from human cell extracts Oncogene High 10918611
2001 Herpes simplex virus 1 ICP0 binds Cdc34 via its RING finger (exon 2) and acts as an E3 ubiquitin ligase that promotes ubiquitination of Cdc34 in vitro; in infected cells, Cdc34 undergoes increased ICP0-dependent dynamic interaction with proteasomes. In vitro ubiquitination assay; RING-domain binding assay; co-immunoprecipitation in infected cells PNAS Medium 11447293
2001 Human CDC34 protein is localized to distinct nuclear and cytoplasmic speckles during interphase; nuclear localization depends on specific C-terminal CDC34 sequences; in anaphase CDC34 colocalizes with β-tubulin at the mitotic spindle. Immunofluorescence; subcellular fractionation; deletion mutant analysis Journal of cell science Medium 10769200
2001 Elevated Cdc34 protein levels at prophase selectively block CENP-E kinesin from associating with kinetochores, causing chromosome congression failure and prometaphase arrest; this effect is not rescued by proteasome inhibitors, suggesting a non-proteolytic ubiquitination role. Microinjection of bacterially expressed Cdc34 into mammalian cells; immunofluorescence; electron microscopy of kinetochores The Journal of cell biology Medium 11514588
2001 Human CDC34 is phosphorylated in proliferating cells; the regulatory β-subunit of CK2 interacts with CDC34 in vivo; recombinant CK2 phosphorylates CDC34 at five C-terminal sites (S203, S222, S231, T233, S236); mutating these sites abolishes in vivo phosphorylation and shifts nuclear CDC34 to the cytoplasm. Yeast two-hybrid; co-immunoprecipitation in transfected cells; in vitro CK2 phosphorylation; site-directed mutagenesis; immunofluorescence The Journal of biological chemistry High 11546811
2003 Formation of the Cdc34-ubiquitin thioester increases the dissociation rate of Cdc34 from the SCF RING domain; release of ubiquitin-charged Cdc34 from the RING is essential for ubiquitination of the SCF(Cdc4)-bound substrate Sic1, as shown by F72V Cdc34 mutant with increased RING affinity that is unable to ubiquitinate Sic1. Kinetic binding measurements; mutagenesis (F72V Cdc34); in vitro ubiquitination assay Cell High 13678584
2003 Cdc34 self-association in vivo depends on integrity of the Cdc34-ubiquitin thioester and key catalytic domain residues (active-site C95, S73, S97, and the catalytic domain insertion); self-association is required for multi-ubiquitin chain assembly and cell cycle function. Co-immunoprecipitation; site-directed mutagenesis of catalytic residues; in vivo complementation Molecular and cellular biology High 12861024
2005 Sic1 ubiquitination by SCF(Cdc4)/Cdc34 occurs in two mechanistically distinct steps: slow rate-limiting attachment of the first ubiquitin, followed by rapid processive elongation of K48-linked chains; an acidic loop conserved in Cdc34 orthologs is required for processivity and K48-linkage specificity during chain elongation but not for first ubiquitin attachment. In vitro ubiquitination assay with purified recombinant proteins; acidic loop mutagenesis; kinetic analysis Cell High 16360039
2005 Proximity-induced dimerization of human Cdc34 (via GST fusion or FKBP-AP20187 chemical dimerization) constitutively activates K48-linked polyubiquitin chain synthesis independently of SCF, suggesting SCF may activate Cdc34 by converting it from an inactive monomer to an active dimer. GST-fusion dimerization; chemical inducer of dimerization (FKBP-AP20187); in vitro ubiquitin chain synthesis assay PNAS Medium 16210246
2007 Human Cdc34 employs distinct sites for mono- vs. polyubiquitination: the conserved charged stretch (residues 143–153) and acidic loop residues D102/D103 are required for Ub-Ub ligation (polychain assembly) but not for substrate monoubiquitination; N85 and S138 coordinate the attacking lysine for catalysis in both steps. Site-directed mutagenesis; in vitro ubiquitination assay with IκBα as substrate; GST-Cdc34 dimerization rescue experiments Molecular and cellular biology High 17698585
2007 CK2 phosphorylates yeast Cdc34 C-terminal tail at S207 and S216 (and human Cdc34 at S203, S222, S231) in vitro; this phosphorylation stimulates Cdc34 ubiquitination activity toward Sic1 in SCFCdc4-dependent reactions; phosphosite alanine mutants with altered activity show corresponding changes in Sic1 degradation and cell cycle progression speed. In vitro CK2 phosphorylation; in vitro ubiquitination assay; yeast cell cycle synchronization and progression assay with cdc34 phosphosite mutants The Biochemical journal High 17461777
2008 CK2 phosphorylates the catalytic domain of Cdc34 at S130 and S167 in vitro and in vivo; these phosphorylation events strongly stimulate Cdc34 ubiquitin-charging activity; the S130A/S167A double mutant fails to complement a cdc34-2ts strain. Mass spectrometry; in vitro CK2 phosphorylation; ubiquitin charging assay; yeast complementation in cka1Δcka2-8ts background Cell cycle High 18418079
2009 The Cdc34 acidic C-terminal tail contributes both to submicromolar binding affinity for SCF(Cdc4) and to catalysis; the functional requirement for the tail is its acidity; Cdc34 retains partial function when fused to the C-terminus of Cul1 even without the tail. Binding affinity measurements; in vitro ubiquitination assay; tail deletion and charge mutants; Cdc34-Cul1 fusion proteins The Journal of biological chemistry High 19875449
2010 Polyubiquitination of IκBα by SCF(βTrCP2) begins with rapid monoubiquitination by UbcH5 at K21/K22, followed by Cdc34-mediated K48-linked polyubiquitin chain elongation using the substrate-linked ubiquitin as a receptor; the IκBα K21-linked ubiquitin makes direct contacts with Cdc34 and the SCF RING subcomplex. Biochemical reconstitution with UbcH5 and Cdc34; ubiquitin-fused substrate constructs; in vitro ubiquitination assay Molecular cell High 20347421
2010 The human Cdc34 C-terminus contains two non-covalent ubiquitin-binding sites (UBS1: residues 206–215; UBS2: 216–225) mapped by NMR; UBS1 aromatic residues (F206, Y207, Y210, Y211) interact near ubiquitin Lys48 and C-terminus; Y210 is specifically required for donor ubiquitin transfer in SCF-dependent reactions. NMR chemical shift perturbation; mutagenesis; in vitro IκBα ubiquitination reconstitution The Journal of biological chemistry High 20353940
2010 Residues surrounding acceptor lysines on Sic1 and ubiquitin are critical for Cdc34-mediated ubiquitination independent of SCF; key residues composing the Cdc34 catalytic core alter lysine preference and determine whether Cdc34 monoubiquitinates or polyubiquitinates Sic1. In vitro ubiquitination assay; mutagenesis of Cdc34 catalytic core residues and substrate lysine-flanking residues Molecular and cellular biology High 20194622
2011 The I44A mutation in ubiquitin profoundly inhibits donor ubiquitin discharge from Cdc34; computationally predicted compensatory mutations in Cdc34 rescue this defect; the Cdc34-ubiquitin interaction at I44 promotes efficient deprotonation of the acceptor lysine for ubiquitin transfer. In vitro ubiquitination assay; site-directed mutagenesis (ubiquitin I44A and Cdc34 compensatory mutants); hydroxylamine acceptor experiments at varying pH Molecular cell High 21474069
2011 A small molecule CC0651 selectively inhibits human Cdc34 by inserting into a cryptic allosteric pocket distant from the catalytic site, causing conformational changes in E2 secondary structure; it does not affect E1 charging or E3 binding but blocks ubiquitin discharge to acceptor lysines; cells show p27(Kip1) accumulation. Crystal structure of Cdc34-CC0651 complex; in vitro ubiquitination assay; cell-based p27 accumulation assay; thioester formation assay Cell High 21683433
2011 The CDC34 C-terminus is intrinsically disordered but intramolecularly interacts with the catalytically bound ubiquitin in the Cdc34-Ub thioester complex; the C-terminus contacts a lysine-rich face of ubiquitin (K6, K11, K29, K33) in a two-state equilibrium, suggesting a role in directing K48-linked chain formation. NMR spectroscopy; CDC34-Ub disulfide mimetic; chemical shift perturbation analysis Journal of molecular biology High 21296085
2013 The Cdc34 acidic loop promotes SCF-Cdc34 interaction and suppresses the pKa of an ionizing species on ubiquitin or Cdc34; two glutamic acid residues on the distal side collaborate with a conserved histidine on the proximal side to promote catalysis. In vitro ubiquitination assay; mutagenesis; pKa measurements; quantification of E2-E3 binding The Journal of biological chemistry High 24129577
2014 The Cdc34-SCF interaction occurs in multiple conformations where several residues from the Cdc34 acidic C-terminal tail contact a broad region of the SCF basic canyon; similar contacts occur with Cul2, implicating a conserved mechanism across cullin-RING ligases. Protein cross-linking followed by mass spectrometry; binding interface mapping The Journal of biological chemistry Medium 25425648
2009 let-7 microRNA directly down-regulates Cdc34 via its 3′-UTR, reducing Cdc34 protein levels, stabilizing the SCF substrate Wee1 kinase, and causing G2/M accumulation in primary human fibroblasts; siRNA knockdown of Wee1 reverses the G2/M phenotype. Luciferase reporter assay (3′-UTR); microarray; siRNA knockdown; Western blot; flow cytometry The Journal of biological chemistry Medium 19126550
2019 Crystal structures of Cdc34 alone, in complex with E1 (Uba1), and as a Cdc34~Ub thioester mimetic reveal: unique E1-binding mode requiring conformational changes in both Uba1 and Cdc34 for transthiolation; the C-terminal extension contacts the catalytically bound ubiquitin, stabilizing a closed conformation critical for ubiquitin discharge. X-ray crystallography (Cdc34 alone, Cdc34-E1 complex, Cdc34~Ub mimetic); mutagenesis; cell-based assays Nature communications High 31341161
2020 CDC34 competes with the E3 ligase c-Cbl to bind EGFR at Y1045, thereby inhibiting EGFR polyubiquitination and degradation and promoting lung carcinogenesis; knockdown of CDC34 inhibits NSCLC tumor formation in mouse models. siRNA library screen; co-immunoprecipitation; overexpression/knockdown in vitro and in vivo xenograft model EBioMedicine Medium 32114396
2010 COP9 signalosome (CSN) protects UBC3/Cdc34 from SCF(βTrCP)-mediated proteasomal degradation; downregulation of CSN4 or CSN5 induces ubiquitination and degradation of Cdc34; this requires the acidic C-terminal extension of Cdc34 which is sufficient to impart SCF(βTrCP)-sensitivity to UBCH5 enzymes. RNAi knockdown of CSN subunits; domain swap (acidic tail transplant onto UBCH5); proteasome inhibitor experiments The Journal of biological chemistry Medium 20378537

Source papers

Stage 0 corpus · 82 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1988 The yeast cell cycle gene CDC34 encodes a ubiquitin-conjugating enzyme. Science (New York, N.Y.) 401 2842867
1999 Cdc53/cullin and the essential Hrt1 RING-H2 subunit of SCF define a ubiquitin ligase module that activates the E2 enzyme Cdc34. Genes & development 352 10385629
2000 Regulation of transcription by ubiquitination without proteolysis: Cdc34/SCF(Met30)-mediated inactivation of the transcription factor Met4. Cell 246 10975521
1998 Cdc53 is a scaffold protein for multiple Cdc34/Skp1/F-box proteincomplexes that regulate cell division and methionine biosynthesis in yeast. Genes & development 241 9499404
2005 Mechanism of lysine 48-linked ubiquitin-chain synthesis by the cullin-RING ubiquitin-ligase complex SCF-Cdc34. Cell 239 16360039
2011 An allosteric inhibitor of the human Cdc34 ubiquitin-conjugating enzyme. Cell 194 21683433
1998 Association of human CUL-1 and ubiquitin-conjugating enzyme CDC34 with the F-box protein p45(SKP2): evidence for evolutionary conservation in the subunit composition of the CDC34-SCF pathway. The EMBO journal 178 9430629
1997 SIC1 is ubiquitinated in vitro by a pathway that requires CDC4, CDC34, and cyclin/CDK activities. Molecular biology of the cell 144 9285816
1998 Cdc34 and the F-box protein Met30 are required for degradation of the Cdk-inhibitory kinase Swe1. Genes & development 129 9716410
1999 A MAP kinase encoded by the ubc3 gene of Ustilago maydis is required for filamentous growth and full virulence. Molecular microbiology 128 10564490
1998 Coupling of mitosis to the completion of S phase through Cdc34-mediated degradation of Wee1. Science (New York, N.Y.) 119 9836638
2010 Priming and extending: a UbcH5/Cdc34 E2 handoff mechanism for polyubiquitination on a SCF substrate. Molecular cell 109 20347421
2011 Essential role for ubiquitin-ubiquitin-conjugating enzyme interaction in ubiquitin discharge from Cdc34 to substrate. Molecular cell 107 21474069
2001 The infected cell protein 0 of herpes simplex virus 1 dynamically interacts with proteasomes, binds and activates the cdc34 E2 ubiquitin-conjugating enzyme, and possesses in vitro E3 ubiquitin ligase activity. Proceedings of the National Academy of Sciences of the United States of America 99 11447293
2009 let-7 Overexpression leads to an increased fraction of cells in G2/M, direct down-regulation of Cdc34, and stabilization of Wee1 kinase in primary fibroblasts. The Journal of biological chemistry 93 19126550
1993 Cloning of the human homolog of the CDC34 cell cycle gene by complementation in yeast. Proceedings of the National Academy of Sciences of the United States of America 90 8248134
1992 A chimeric ubiquitin conjugating enzyme that combines the cell cycle properties of CDC34 (UBC3) and the DNA repair properties of RAD6 (UBC2): implications for the structure, function and evolution of the E2s. The EMBO journal 87 1639076
1993 The bacterially expressed yeast CDC34 gene product can undergo autoubiquitination to form a multiubiquitin chain-linked protein. The Journal of biological chemistry 85 8383676
1991 Ubiquitin conjugation by the yeast RAD6 and CDC34 gene products. Comparison to their putative rabbit homologs, E2(20K) AND E2(32K). The Journal of biological chemistry 74 1848239
2000 Degradation of B-Myb by ubiquitin-mediated proteolysis: involvement of the Cdc34-SCF(p45Skp2) pathway. Oncogene 73 10871850
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