The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.

wikigene or wiki gene protein drug chemical gene disease author authorship tracking collaborative publishing evolutionary knowledge reputation system wiki2.0 global collaboration genes proteins drugs chemicals diseases compound
Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)



Gene Review

CLB2  -  Clb2p

Saccharomyces cerevisiae S288c

Synonyms: G2/mitotic-specific cyclin-2, P9642.6, YPR119W
Welcome! If you are familiar with the subject of this article, you can contribute to this open access knowledge base by deleting incorrect information, restructuring or completely rewriting any text. Read more.

High impact information on CLB2

  • Yeast Hct1 is a regulator of Clb2 cyclin proteolysis [1].
  • Remarkably, Clb2-Cdc28 activity remains elevated in the overreplicating cells [2].
  • Proteolysis of CLB2 is initiated in early anaphase, but a fraction of CLB2 remains stable until anaphase is complete [3].
  • Neither CLB1 nor CLB2 is essential; however, disruption of both is lethal and causes a mitotic defect [4].
  • Fkh2 protein is associated with the promoters of CLB2, SWI5 and other genes of the cluster [5].

Biological context of CLB2

  • We show here that CLB2 proteolysis, which is important for transition from mitosis to G1, is not confined to a narrow window at the end of mitosis as previously thought but continues until reactivation of CDC28 by CLN cyclins toward the end of the subsequent G1 period [6].
  • This cell cycle arrest can be overcome and partial suppression of the ts phenotype of rts1-null cells occurs if the gene CLB2, encoding a Cdc28 kinase-associated B-type cyclin, is expressed on a high-copy-number plasmid [7].
  • However, CLB2 overexpression has no suppressive effects on other aspects of the rts1-null phenotype [7].
  • Overproduction of Ndd1 also enhances the expression of SWI5, whose transcription, like that of CLB1 and CLB2, is activated in the late S phase [8].
  • BACKGROUND: The 'CLB2 cluster' in Saccharomyces cerevisiae consists of approximately 33 genes whose transcription peaks in late G2/early M phase of the cell cycle [9].

Anatomical context of CLB2

  • Our experiments also suggest that NAP1 is required for the ability of the Clb2/p34CDC28 kinase complex to amplify its own production, and that NAP1 plays a role in regulation of microtubule dynamics during mitosis [10].

Associations of CLB2 with chemical compounds

  • A malachite green binding motif, defined by an asymmetric internal loop flanked by short RNA helices, was inserted immediately upstream of the CLB2 start codon [11].
  • We report here that cells expressing cdc28-E19 (in which Tyr-19 is replaced by glutamic acid) perform Start-related functions, complete DNA synthesis, and exhibit high levels of Clb2-associated kinase activity but are unable to form bipolar spindles [12].
  • A point mutation in a potential leucine-rich nuclear export signal (NES) enhances the nuclear localization of the protein, and delta-yrb2 cells exhibit an apparent Clb2p nuclear export defect [13].
  • The proline-directed phosphatase, Cdc14p, is a key component of MEN and promotes mitotic exit by activating the degradation of Clb2p and by reversing Cdk-mediated mitotic phosphorylation [14].

Physical interactions of CLB2

  • Instead, overexpression of NDD1 prevents the formation of one of the complexes whose appearance correlates with the termination of CLB2 expression in G1 [8].
  • The essential transcription factor Reb1p interacts with the CLB2 UAS outside of the G2/M control region [15].
  • The forkhead transcription factor Fkh2p acts in a DNA-bound complex with Mcm1p and the coactivator Ndd1p to regulate cell cycle-dependent expression of the CLB2 gene cluster in Saccharomyces cerevisiae [16].
  • Active Clb2-Cdc28 kinase complex was purified from yeast cells after inserting the CHH tag into Clb2 [17].

Co-localisations of CLB2


Regulatory relationships of CLB2

  • We replaced the early-expressed CLB5 coding sequence with the late-expressed CLB2 coding sequence, at the CLB5 locus [19].
  • Genetic experiments revealed that loss of either Clb5p or Clb2p cyclins suppresses the mcm5-bob1 mutation and prevents bypass [20].
  • In Saccharomyces cerevisiae, Fkh2 both activates and represses transcription of CLB2, encoding a B-type cyclin [21].
  • These data show that PKA pathways regulate mitotic progression through Cdc20 and support the DNA damage checkpoint pathways in regulating the destruction of Clb2 and securin [22].
  • Furthermore, we find that inactivation of Cln- and Clb-Cdc28 kinases is sufficient to trigger Clb2 proteolysis and sister-chromatid separation in G2/M phase-arrested cells, where the B-type cyclin-specific proteolysis machinery is normally inactive [23].

Other interactions of CLB2

  • CLB5 transcript abundance peaks in G1, coincident with the CLN2 transcript but earlier than the CLB2 transcript [24].
  • They are most related to each other and then to the deduced protein sequence of their adjacent genes CLB1 and CLB2 [25].
  • However, constitutive CLB2 expression does not suppress the mitotic defect, and therefore other essential activities required for the G2-to-M transition must also depend on Mcm1 function [26].
  • The Rad50 pathway was more sensitive to the absence of Clb2 than the Rad51 pathway [27].
  • We show that both FKH1 and FKH2 play essential roles in the activation of the CLB2 cluster genes during G2-M and in establishing their transcriptional periodicity [9].

Analytical, diagnostic and therapeutic context of CLB2


  1. Yeast Hct1 is a regulator of Clb2 cyclin proteolysis. Schwab, M., Lutum, A.S., Seufert, W. Cell (1997) [Pubmed]
  2. The yeast CDC16 and CDC27 genes restrict DNA replication to once per cell cycle. Heichman, K.A., Roberts, J.M. Cell (1996) [Pubmed]
  3. Genes involved in sister chromatid separation are needed for B-type cyclin proteolysis in budding yeast. Irniger, S., Piatti, S., Michaelis, C., Nasmyth, K. Cell (1995) [Pubmed]
  4. The role of CDC28 and cyclins during mitosis in the budding yeast S. cerevisiae. Surana, U., Robitsch, H., Price, C., Schuster, T., Fitch, I., Futcher, A.B., Nasmyth, K. Cell (1991) [Pubmed]
  5. Two yeast forkhead genes regulate the cell cycle and pseudohyphal growth. Zhu, G., Spellman, P.T., Volpe, T., Brown, P.O., Botstein, D., Davis, T.N., Futcher, B. Nature (2000) [Pubmed]
  6. Closing the cell cycle circle in yeast: G2 cyclin proteolysis initiated at mitosis persists until the activation of G1 cyclins in the next cycle. Amon, A., Irniger, S., Nasmyth, K. Cell (1994) [Pubmed]
  7. Molecular genetic analysis of Rts1p, a B' regulatory subunit of Saccharomyces cerevisiae protein phosphatase 2A. Shu, Y., Yang, H., Hallberg, E., Hallberg, R. Mol. Cell. Biol. (1997) [Pubmed]
  8. NDD1, a high-dosage suppressor of cdc28-1N, is essential for expression of a subset of late-S-phase-specific genes in Saccharomyces cerevisiae. Loy, C.J., Lydall, D., Surana, U. Mol. Cell. Biol. (1999) [Pubmed]
  9. Forkhead transcription factors, Fkh1p and Fkh2p, collaborate with Mcm1p to control transcription required for M-phase. Kumar, R., Reynolds, D.M., Shevchenko, A., Shevchenko, A., Goldstone, S.D., Dalton, S. Curr. Biol. (2000) [Pubmed]
  10. NAP1 acts with Clb1 to perform mitotic functions and to suppress polar bud growth in budding yeast. Kellogg, D.R., Murray, A.W. J. Cell Biol. (1995) [Pubmed]
  11. Inducible regulation of the S. cerevisiae cell cycle mediated by an RNA aptamer-ligand complex. Grate, D., Wilson, C. Bioorg. Med. Chem. (2001) [Pubmed]
  12. Spindle pole body separation in Saccharomyces cerevisiae requires dephosphorylation of the tyrosine 19 residue of Cdc28. Lim, H.H., Goh, P.Y., Surana, U. Mol. Cell. Biol. (1996) [Pubmed]
  13. The Saccharomyces cerevisiae cyclin Clb2p is targeted to multiple subcellular locations by cis- and trans-acting determinants. Hood, J.K., Hwang, W.W., Silver, P.A. J. Cell. Sci. (2001) [Pubmed]
  14. Crm1-mediated nuclear export of Cdc14 is required for the completion of cytokinesis in budding yeast. Bembenek, J., Kang, J., Kurischko, C., Li, B., Raab, J.R., Belanger, K.D., Luca, F.C., Yu, H. Cell Cycle (2005) [Pubmed]
  15. The essential transcription factor Reb1p interacts with the CLB2 UAS outside of the G2/M control region. Van Slyke, C., Grayhack, E.J. Nucleic Acids Res. (2003) [Pubmed]
  16. Regulation of cell cycle-specific gene expression through cyclin-dependent kinase-mediated phosphorylation of the forkhead transcription factor Fkh2p. Pic-Taylor, A., Darieva, Z., Morgan, B.A., Sharrocks, A.D. Mol. Cell. Biol. (2004) [Pubmed]
  17. A novel multiple affinity purification tag and its use in identification of proteins associated with a cyclin-CDK complex. Honey, S., Schneider, B.L., Schieltz, D.M., Yates, J.R., Futcher, B. Nucleic Acids Res. (2001) [Pubmed]
  18. Differential cellular localization among mitotic cyclins from Saccharomyces cerevisiae: a new role for the axial budding protein Bud3 in targeting Clb2 to the mother-bud neck. Bailly, E., Cabantous, S., Sondaz, D., Bernadac, A., Simon, M.N. J. Cell. Sci. (2003) [Pubmed]
  19. Specialization and targeting of B-type cyclins. Cross, F.R., Yuste-Rojas, M., Gray, S., Jacobson, M.D. Mol. Cell (1999) [Pubmed]
  20. The mcm5-bob1 bypass of Cdc7p/Dbf4p in DNA replication depends on both Cdk1-independent and Cdk1-dependent steps in Saccharomyces cerevisiae. Sclafani, R.A., Tecklenburg, M., Pierce, A. Genetics (2002) [Pubmed]
  21. The Isw2 Chromatin-Remodeling ATPase Cooperates with the Fkh2 Transcription Factor To Repress Transcription of the B-Type Cyclin Gene CLB2. Sherriff, J.A., Kent, N.A., Mellor, J. Mol. Cell. Biol. (2007) [Pubmed]
  22. The DNA damage checkpoint and PKA pathways converge on APC substrates and Cdc20 to regulate mitotic progression. Searle, J.S., Schollaert, K.L., Wilkins, B.J., Sanchez, Y. Nat. Cell Biol. (2004) [Pubmed]
  23. Regulation of B-type cyclin proteolysis by Cdc28-associated kinases in budding yeast. Amon, A. EMBO J. (1997) [Pubmed]
  24. CLB5: a novel B cyclin from budding yeast with a role in S phase. Epstein, C.B., Cross, F.R. Genes Dev. (1992) [Pubmed]
  25. A new pair of B-type cyclins from Saccharomyces cerevisiae that function early in the cell cycle. Kühne, C., Linder, P. EMBO J. (1993) [Pubmed]
  26. Mcm1 is required to coordinate G2-specific transcription in Saccharomyces cerevisiae. Althoefer, H., Schleiffer, A., Wassmann, K., Nordheim, A., Ammerer, G. Mol. Cell. Biol. (1995) [Pubmed]
  27. Mitotic cyclins regulate telomeric recombination in telomerase-deficient yeast cells. Grandin, N., Charbonneau, M. Mol. Cell. Biol. (2003) [Pubmed]
  28. Assaying the spindle checkpoint in the budding yeast Saccharomyces cerevisiae. Yellman, C.M., Burke, D.J. Methods Mol. Biol. (2004) [Pubmed]
WikiGenes - Universities