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Gene Review

SSN3  -  Ssn3p

Saccharomyces cerevisiae S288c

Synonyms: ARE1, CDK8, Cyclin-dependent kinase 8, GIG2, Meiotic mRNA stability protein kinase SSN3, ...
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High impact information on SSN3

  • This indicates that Srb10 controls Ste12 activity for filamentous growth in response to nitrogen limitation and is consistent with the hypothesis that Srb10 regulates gene-specific activators in response to physiological signals to coordinate gene expression with growth potential [1].
  • Mutation of the Srb10-dependent phosphorylation sites increases pseudohyphal development but has no effect on the pheromone response of haploid yeast [1].
  • Genetic and biochemical evidence indicates that the SRB10 and SRB11 proteins form a kinase-cyclin pair in the holoenzyme [2].
  • The SRB10/11 kinase is essential for a normal transcriptional response to galactose induction in vivo [2].
  • Negative regulation of Gcn4 and Msn2 transcription factors by Srb10 cyclin-dependent kinase [3].

Biological context of SSN3


Associations of SSN3 with chemical compounds

  • Mutations in SSN3 and SSN8 also act synergistically with a mutation of the MIG1 repressor protein to relieve glucose repression [8].
  • Here, we show that the cyclin-dependent kinase Srb10 interacts with, and phosphorylates, the Med2 subunit of Mediator both in vivo and in vitro [6].
  • The candidate kinases Kin28-Ccl1, CTDK1, and Srb10-Srb11 can each phosphorylate a glutathione S-transferase-CTD fusion protein such that capping enzyme can bind in vitro [9].
  • The UME5 gene encodes a predicted 63-kDa protein with homology to the family of CDC28 serine/threonine-specific protein kinases [10].
  • Accordingly, the ARE1 promoter is upregulated in strains that accumulate ergosterol precursors [11].

Physical interactions of SSN3

  • Proteins in the Med9 submodule interact physically and genetically with Srb10/11, suggesting that the Med9 submodule mediates the repression of pol II [12].

Enzymatic interactions of SSN3

  • Srb10 inhibits filamentous growth in cells growing in rich medium by phosphorylating Ste12 and decreasing its stability [1].
  • In addition to the previously known substrate, the Pol II CTD, it was found that Kin28 phosphorylates two subunits of Mediator and Srb10 targets two subunits of TFIID for phosphorylation [13].

Regulatory relationships of SSN3

  • These genes are activated by Msn2 and repressed by the Srb10 kinase, a member of the mediator complex [7].
  • Turnover of Hac1p may be dependent on transcription because it is inhibited in cell mutants lacking Srb10 kinase, a component of the SRB/mediator module of the RNA polymerase II holoenzyme [14].

Other interactions of SSN3

  • We have cloned the SSN3 and SSN8 genes [8].
  • The SSN3 and SSN8 genes of Saccharomyces cerevisiae were identified by mutations that suppress a defect in SNF1, a protein kinase required for release from glucose repression [8].
  • SRB10 and GAL3 are shown to represent parallel mechanisms for GAL gene induction [4].
  • We have isolated three deletion mutants, srb10, srb11 and saf1 (ybr280c) affecting AAH1 expression during post-diauxic growth and in early stationary phase [15].
  • With regard to the effect brought about by the deletion of rox1 and srb10, correspondence cluster analysis revealed that the transcriptome profile in aerobic conditions is very similar in the wild-type and both deletion strains [16].

Analytical, diagnostic and therapeutic context of SSN3

  • The complex was purified by two different methods: conventional chromatography and affinity chromatography using antibodies directed against CDK8, the human homolog of the yeast Srb10 protein [17].


  1. Srb10/Cdk8 regulates yeast filamentous growth by phosphorylating the transcription factor Ste12. Nelson, C., Goto, S., Lund, K., Hung, W., Sadowski, I. Nature (2003) [Pubmed]
  2. A kinase-cyclin pair in the RNA polymerase II holoenzyme. Liao, S.M., Zhang, J., Jeffery, D.A., Koleske, A.J., Thompson, C.M., Chao, D.M., Viljoen, M., van Vuuren, H.J., Young, R.A. Nature (1995) [Pubmed]
  3. Negative regulation of Gcn4 and Msn2 transcription factors by Srb10 cyclin-dependent kinase. Chi, Y., Huddleston, M.J., Zhang, X., Young, R.A., Annan, R.S., Carr, S.A., Deshaies, R.J. Genes Dev. (2001) [Pubmed]
  4. Multiple signals regulate GAL transcription in yeast. Rohde, J.R., Trinh, J., Sadowski, I. Mol. Cell. Biol. (2000) [Pubmed]
  5. Genetic analysis of the role of Pol II holoenzyme components in repression by the Cyc8-Tup1 corepressor in yeast. Lee, M., Chatterjee, S., Struhl, K. Genetics (2000) [Pubmed]
  6. Site-specific Srb10-dependent phosphorylation of the yeast Mediator subunit Med2 regulates gene expression from the 2-microm plasmid. Hallberg, M., Polozkov, G.V., Hu, G.Z., Beve, J., Gustafsson, C.M., Ronne, H., Björklund, S. Proc. Natl. Acad. Sci. U.S.A. (2004) [Pubmed]
  7. Genetic factors that regulate the attenuation of the general stress response of yeast. Bose, S., Dutko, J.A., Zitomer, R.S. Genetics (2005) [Pubmed]
  8. Cyclin-dependent protein kinase and cyclin homologs SSN3 and SSN8 contribute to transcriptional control in yeast. Kuchin, S., Yeghiayan, P., Carlson, M. Proc. Natl. Acad. Sci. U.S.A. (1995) [Pubmed]
  9. Kin28, the TFIIH-associated carboxy-terminal domain kinase, facilitates the recruitment of mRNA processing machinery to RNA polymerase II. Rodriguez, C.R., Cho, E.J., Keogh, M.C., Moore, C.L., Greenleaf, A.L., Buratowski, S. Mol. Cell. Biol. (2000) [Pubmed]
  10. The yeast UME5 gene regulates the stability of meiotic mRNAs in response to glucose. Surosky, R.T., Strich, R., Esposito, R.E. Mol. Cell. Biol. (1994) [Pubmed]
  11. Transcriptional regulation of the two sterol esterification genes in the yeast Saccharomyces cerevisiae. Jensen-Pergakes, K., Guo, Z., Giattina, M., Sturley, S.L., Bard, M. J. Bacteriol. (2001) [Pubmed]
  12. The structural and functional organization of the yeast mediator complex. Kang, J.S., Kim, S.H., Hwang, M.S., Han, S.J., Lee, Y.C., Kim, Y.J. J. Biol. Chem. (2001) [Pubmed]
  13. Two cyclin-dependent kinases promote RNA polymerase II transcription and formation of the scaffold complex. Liu, Y., Kung, C., Fishburn, J., Ansari, A.Z., Shokat, K.M., Hahn, S. Mol. Cell. Biol. (2004) [Pubmed]
  14. SCFCdc4-mediated Degradation of the Hac1p Transcription Factor Regulates the Unfolded Protein Response in Saccharomyces cerevisiae. Pal, B., Chan, N.C., Helfenbaum, L., Tan, K., Tansey, W.P., Gething, M.J. Mol. Biol. Cell (2007) [Pubmed]
  15. Proteasome- and SCF-dependent degradation of yeast adenine deaminase upon transition from proliferation to quiescence requires a new F-box protein named Saf1p. Escusa, S., Camblong, J., Galan, J.M., Pinson, B., Daignan-Fornier, B. Mol. Microbiol. (2006) [Pubmed]
  16. The yeast transcriptome in aerobic and hypoxic conditions: effects of hap1, rox1, rox3 and srb10 deletions. Becerra, M., Lombardía-Ferreira, L.J., Hauser, N.C., Hoheisel, J.D., Tizon, B., Cerdán, M.E. Mol. Microbiol. (2002) [Pubmed]
  17. A human RNA polymerase II complex containing factors that modify chromatin structure. Cho, H., Orphanides, G., Sun, X., Yang, X.J., Ogryzko, V., Lees, E., Nakatani, Y., Reinberg, D. Mol. Cell. Biol. (1998) [Pubmed]
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