CDC34/YDR054C Summary Help

Standard Name CDC34 1
Systematic Name YDR054C
Alias DNA6 2 , UBC3 3
Feature Type ORF, Verified
Description Ubiquitin-conjugating enzyme (E2); catalytic subunit of SCF ubiquitin-protein ligase complex (together with Skp1p, Rbx1p, Cdc53p, and an F-box protein) that regulates cell cycle progression by targeting key substrates for degradation; protein abundance increases in response to DNA replication stress (4, 5 and see Summary Paragraph)
Name Description Cell Division Cycle
Chromosomal Location
ChrIV:562327 to 561440 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: 37 cM
Gene Ontology Annotations All CDC34 GO evidence and references
  View Computational GO annotations for CDC34
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 9 genes
Classical genetics
Large-scale survey
reduction of function
268 total interaction(s) for 177 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 29
  • Affinity Capture-RNA: 3
  • Affinity Capture-Western: 17
  • Biochemical Activity: 21
  • Co-crystal Structure: 1
  • Co-fractionation: 2
  • FRET: 1
  • Reconstituted Complex: 18
  • Two-hybrid: 1

Genetic Interactions
  • Dosage Growth Defect: 2
  • Dosage Lethality: 6
  • Dosage Rescue: 13
  • Negative Genetic: 1
  • Phenotypic Enhancement: 5
  • Phenotypic Suppression: 6
  • Positive Genetic: 1
  • Synthetic Growth Defect: 53
  • Synthetic Haploinsufficiency: 2
  • Synthetic Lethality: 71
  • Synthetic Rescue: 15

Expression Summary
Length (a.a.) 295
Molecular Weight (Da) 34,064
Isoelectric Point (pI) 3.97
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrIV:562327 to 561440 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: 37 cM
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..888 562327..561440 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | E.C. | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000002461

CDC34 encodes a ubiquitin-conjugating enzyme (Ubc/E2) that catalyzes Skp1-Cullin-F-box (SCF) ubiquitin protein ligase-mediated substrate ubiquitination (3, 6, 7). SCF-mediated ubiquitination involves three sequential enzymatic steps: ATP-dependent activation of ubiquitin through the formation of a high-energy thioester linkage with a ubiquitin-activating enzyme (E1); transfer of the activated ubiquitin to a ubiquitin-conjugating enzyme (E2); and the E2-catalyzed transfer of activated ubiquitin to a specific lysine residue(s) of the target protein, aided by substrate-specific components of SCF ubiquitin protein ligase complexes (E3s). This sequence is repeated until multiple chains of ubiquitin are attached, thereby marking the protein for rapid degradation by the 26S proteasome (reviewed in 8 and 4).

SCF ubiquitin protein ligases are RING-H2 type ligase family members that function as target recognition modules, bringing Cdc34p and substrates into close proximity, thereby positioning Cdc34p for efficient transfer of activated ubiquitin (reviewed in 4, 9 and 10). SCF ubiquitin ligase core complexes are composed of several shared subunits including Skp1p, an adaptor protein that binds and recruits a variety of F-box containing proteins (11, 7); Cdc53p, a cullin family member that recruits Cdc34p to Skp1p/F-box proteins (12, 13, 14); Hrt1p, a RING-H2 domain protein that stimulates ubiquitin-ligase activity (15, 16); and Cdc34p, a ubiquitin-conjugating enzyme that catalyzes the transfer of activated ubiquitin to the target protein (3, 6, 7). In addition to these shared subunits SCF complexes also contain one of several unique F-box motif containing proteins (Cdc4p, Grr1p, Met30p, Dia2p, or Saf1p) that function as substrate-specific adaptors or specificity determinants recruiting multiply phosphorylated substrates to the SCF core complex (reviewed in 4, 17 and 18). Multiple SCF-F-box specific substrates have been identified. SCF-Cdc4p facilitates the polyubiquitination of Sic1p (6, 7), Far1p (19, 20), Cdc6p (21, 22), Clb6p (23) and Hac1p (24); substrates of SCF-Grr1p include Cln1p, Cln2p (13, 25, 26), Gic1p, and Gic2p (27); substrates of SCF-Met30p include Met4p (28) and Swe1p (29); SCF-Dia2p polyubiquitinates Tec1p (30); and SCF-Saf1p polyubiquitinates Aah1p (31, 32). The F-box proteins Cdc4p, Grr1p, and Met30p are also intrinsically unstable and are able to catalyze their own SCF-mediated ubiquitination and destruction via an autocatalytic mechanism proposed to facilitate rapid switching among multiple SCF complexes (33, 34). As a component of the SCF core complex, Cdc34p has been directly implicated in the ubiquitin-mediated proteolysis of all of the substrates listed above (26, 13, 12, 35, 21, 23, 12, 36, 29, 37, 12, 19, 24, 27, 30, 31).

cdc34 was originally identified as a cell division cycle (CDC) mutant that arrests at the G1/S phase transition with multiple elongated buds and unreplicated DNA, similar to cdc4, cdc53 and hrt1 mutants (14, 3, 16, 38). Deletion of the CDK inhibitor SIC1 alters the terminal phenotype of cdc34, cdc53 and cdc4 mutants, resulting in cells that now arrest at the G2/M phase transition of the cell cycle with replicated DNA and a single round bud (27, 39). It is therefore the accumulation of this SCF substrate (Sic1p) that is solely responsible for the failure of these mutants to enter into S phase, and emphasizes the importance of ubiquitin-mediated proteolysis for regulated passage through key cell cycle transitions.

Cdc34p is regulated by phosphorylation, autoubiquitination and self-association (38, 40, 41). The carboxy-terminal tail of Cdc34p is phosphorylated on serine residues by casein kinase 2 (a tetrameric enzyme containing Cka1p, Cka2p, Ckb1p, and Ckb2p), and phophorylation regulates the intrinsic catalytic activity of the enzyme and its activity when assayed in the presence of SCF-Cdc4p (42). The modulation of Cdc34p activity in turn affects the expression of methionine (MET) biosynthetic genes (43, 44) as well as cell cycle progression (42), due to effects on Cdc34p substrates. Cdc34p is also able to catalyze its own ubiquitination via a mechanism that involves intramolecular transfer of the thiol-ester linked ubiquitin to a C-terminal lysine residue (40). Autoubiquitination of Cdc34p is stimulated by SCF, or by a Cdc53p-Hrt1p subcomplex (26, 15), although the regulatory importance of this modification has yet to be determined. Cdc34p interacts with itself in a ubiquitin-thiolester formation dependent manner and self-association is required for both its catalytic activity and its cell cycle function (41, 45).

CDC34 is evolutionarily conserved and a human CDC34 homolog (OMIM) has been identified based on functional complementation (46, 47). The subunit composition of the human SCF ubiquitin protein ligase is also conserved (48), and like Cdc34p, the human protein is phosphorylated by casein kinase 2 (49). Substrates of the human protein include oncoproteins and tumor suppressors (47, 50, 51).

Last updated: 2007-06-14 Contact SGD

References cited on this page View Complete Literature Guide for CDC34
1) Goebl, M.G.  (1989) Personal Communication, Mortimer Map Edition 10
2) Dumas LB, et al.  (1982) New temperature-sensitive mutants of Saccharomyces cerevisiae affecting DNA replication. Mol Gen Genet 187(1):42-6
3) Goebl MG, et al.  (1988) The yeast cell cycle gene CDC34 encodes a ubiquitin-conjugating enzyme. Science 241(4871):1331-5
4) Craig KL and Tyers M  (1999) The F-box: a new motif for ubiquitin dependent proteolysis in cell cycle regulation and signal transduction. Prog Biophys Mol Biol 72(3):299-328
5) Tkach JM, et al.  (2012) Dissecting DNA damage response pathways by analysing protein localization and abundance changes during DNA replication stress. Nat Cell Biol 14(9):966-76
6) Feldman RM, et al.  (1997) A complex of Cdc4p, Skp1p, and Cdc53p/cullin catalyzes ubiquitination of the phosphorylated CDK inhibitor Sic1p. Cell 91(2):221-30
7) Skowyra D, et al.  (1997) F-box proteins are receptors that recruit phosphorylated substrates to the SCF ubiquitin-ligase complex. Cell 91(2):209-19
8) Hershko A  (1997) Roles of ubiquitin-mediated proteolysis in cell cycle control. Curr Opin Cell Biol 9(6):788-99
9) Kamura T, et al.  (2002) Roles of SCF and VHL ubiquitin ligases in regulation of cell growth. Prog Mol Subcell Biol 29:1-15
10) Jackson PK  (1996) Cell cycle: cull and destroy. Curr Biol 6(10):1209-12
11) Bai C, et al.  (1996) SKP1 connects cell cycle regulators to the ubiquitin proteolysis machinery through a novel motif, the F-box. Cell 86(2):263-74
12) Patton EE, et al.  (1998) Cdc53 is a scaffold protein for multiple Cdc34/Skp1/F-box proteincomplexes that regulate cell division and methionine biosynthesis in yeast. Genes Dev 12(5):692-705
13) Willems AR, et al.  (1996) Cdc53 targets phosphorylated G1 cyclins for degradation by the ubiquitin proteolytic pathway. Cell 86(3):453-63
14) Mathias N, et al.  (1996) Cdc53p acts in concert with Cdc4p and Cdc34p to control the G1-to-S-phase transition and identifies a conserved family of proteins. Mol Cell Biol 16(12):6634-43
15) Seol JH, et al.  (1999) Cdc53/cullin and the essential Hrt1 RING-H2 subunit of SCF define a ubiquitin ligase module that activates the E2 enzyme Cdc34. Genes Dev 13(12):1614-26
16) Ohta T, et al.  (1999) ROC1, a homolog of APC11, represents a family of cullin partners with an associated ubiquitin ligase activity. Mol Cell 3(4):535-41
17) Patton EE, et al.  (1998) Combinatorial control in ubiquitin-dependent proteolysis: don't Skp the F-box hypothesis. Trends Genet 14(6):236-43
18) Willems AR, et al.  (1999) SCF ubiquitin protein ligases and phosphorylation-dependent proteolysis. Philos Trans R Soc Lond B Biol Sci 354(1389):1533-50
19) Henchoz S, et al.  (1997) Phosphorylation- and ubiquitin-dependent degradation of the cyclin-dependent kinase inhibitor Far1p in budding yeast. Genes Dev 11(22):3046-60
20) Blondel M, et al.  (2000) Nuclear-specific degradation of Far1 is controlled by the localization of the F-box protein Cdc4. EMBO J 19(22):6085-97
21) Drury LS, et al.  (1997) The Cdc4/34/53 pathway targets Cdc6p for proteolysis in budding yeast. EMBO J 16(19):5966-76
22) Sanchez M, et al.  (1999) The Cdc6 protein is ubiquitinated in vivo for proteolysis in Saccharomyces cerevisiae. J Biol Chem 274(13):9092-7
23) Jackson LP, et al.  (2006) Distinct mechanisms control the stability of the related S-phase cyclins Clb5 and Clb6. Mol Cell Biol 26(6):2456-66
24) Pal B, et al.  (2007) SCFCdc4-mediated degradation of the Hac1p transcription factor regulates the unfolded protein response in Saccharomyces cerevisiae. Mol Biol Cell 18(2):426-40
25) Barral Y, et al.  (1995) G1 cyclin turnover and nutrient uptake are controlled by a common pathway in yeast. Genes Dev 9(4):399-409
26) Skowyra D, et al.  (1999) Reconstitution of G1 cyclin ubiquitination with complexes containing SCFGrr1 and Rbx1. Science 284(5414):662-5
27) Jaquenoud M, et al.  (1998) The Cdc42p effector Gic2p is targeted for ubiquitin-dependent degradation by the SCFGrr1 complex. EMBO J 17(18):5360-73
28) Rouillon A, et al.  (2000) Feedback-regulated degradation of the transcriptional activator Met4 is triggered by the SCF(Met30 )complex. EMBO J 19(2):282-94
29) Kaiser P, et al.  (1998) Cdc34 and the F-box protein Met30 are required for degradation of the Cdk-inhibitory kinase Swe1. Genes Dev 12(16):2587-97
30) Bao MZ, et al.  (2004) Pheromone-dependent destruction of the Tec1 transcription factor is required for MAP kinase signaling specificity in yeast. Cell 119(7):991-1000
31) Escusa S, et al.  (2006) Proteasome- and SCF-dependent degradation of yeast adenine deaminase upon transition from proliferation to quiescence requires a new F-box protein named Saf1p. Mol Microbiol 60(4):1014-25
32) Escusa S, et al.  (2007) Skp1-Cullin-F-box-dependent Degradation of Aah1p Requires Its Interaction with the F-box Protein Saf1p. J Biol Chem 282(28):20097-103
33) Galan JM and Peter M  (1999) Ubiquitin-dependent degradation of multiple F-box proteins by an autocatalytic mechanism. Proc Natl Acad Sci U S A 96(16):9124-9
34) Zhou P and Howley PM  (1998) Ubiquitination and degradation of the substrate recognition subunits of SCF ubiquitin-protein ligases. Mol Cell 2(5):571-80
35) Yaglom J, et al.  (1995) p34Cdc28-mediated control of Cln3 cyclin degradation. Mol Cell Biol 15(2):731-41
36) Verma R, et al.  (1997) SIC1 is ubiquitinated in vitro by a pathway that requires CDC4, CDC34, and cyclin/CDK activities. Mol Biol Cell 8(8):1427-37
37) Kaiser P, et al.  (2000) Regulation of transcription by ubiquitination without proteolysis: Cdc34/SCF(Met30)-mediated inactivation of the transcription factor Met4. Cell 102(3):303-14
38) Goebl MG, et al.  (1994) The Ubc3 (Cdc34) ubiquitin-conjugating enzyme is ubiquitinated and phosphorylated in vivo. Mol Cell Biol 14(5):3022-9
39) Schwob E, et al.  (1994) The B-type cyclin kinase inhibitor p40SIC1 controls the G1 to S transition in S. cerevisiae. Cell 79(2):233-44
40) Banerjee A, et al.  (1993) The bacterially expressed yeast CDC34 gene product can undergo autoubiquitination to form a multiubiquitin chain-linked protein. J Biol Chem 268(8):5668-75
41) Ptak C, et al.  (1994) Functional and physical characterization of the cell cycle ubiquitin-conjugating enzyme CDC34 (UBC3). Identification of a functional determinant within the tail that facilitates CDC34 self-association. J Biol Chem 269(42):26539-45
42) Sadowski M, et al.  (2007) Cdc34 C-terminal tail phosphorylation regulates Skp1/cullin/F-box (SCF)-mediated ubiquitination and cell cycle progression. Biochem J 405(3):569-81
43) Pyerin W, et al.  (2005) Protein kinase CK2 in gene control at cell cycle entry. Mol Cell Biochem 274(1-2):189-200
44) Barz T, et al.  (2006) Control of methionine biosynthesis genes by protein kinase CK2-mediated phosphorylation of Cdc34. Cell Mol Life Sci 63(18):2183-90
45) Varelas X, et al.  (2003) Cdc34 self-association is facilitated by ubiquitin thiolester formation and is required for its catalytic activity. Mol Cell Biol 23(15):5388-400
46) Plon SE, et al.  (1993) Cloning of the human homolog of the CDC34 cell cycle gene by complementation in yeast. Proc Natl Acad Sci U S A 90(22):10484-8
47) Block K, et al.  (2005) The acidic tail domain of human Cdc34 is required for p27Kip1 ubiquitination and complementation of a cdc34 temperature sensitive yeast strain. Cell Cycle 4(10):1421-7
48) Lisztwan J, et al.  (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. EMBO J 17(2):368-83
49) Block K, et al.  (2001) Phosphorylation of the human ubiquitin-conjugating enzyme, CDC34, by casein kinase 2. J Biol Chem 276(44):41049-58
50) Charrasse S, et al.  (2000) Degradation of B-Myb by ubiquitin-mediated proteolysis: involvement of the Cdc34-SCF(p45Skp2) pathway. Oncogene 19(26):2986-95
51) Macdonald M, et al.  (2004) Control of cell cycle-dependent degradation of c-Ski proto-oncoprotein by Cdc34. Oncogene 23(33):5643-53