GAL4 Is Regulated by the RNA Polymerase II Holoenzyme-Associated Cyclin-Dependent Protein Kinase SRB10/CDK8

Mol Cell. 1999 May;3(5):673-8. doi: 10.1016/s1097-2765(00)80360-3.


Phosphorylation of the yeast transcription factor GAL4 at S699 is required for efficient galactose-inducible transcription. We demonstrate that this site is a substrate for the RNA polymerase holoenzyme-associated CDK SRB10. S699 phosphorylation requires SRB10 in vivo, and this site is phosphorylated by purified SRB10/ SRB11 CDK/cyclin in vitro. RNA Pol II holoenzymes purified from WT yeast phosphorylate GAL4 at sites observed in vivo whereas holoenzymes from srb10 yeast are incapable of phosphorylating GAL4 at S699. Mutations at GAL4 S699 and srb10 are epistatic for GAL induction, demonstrating that SRB10 regulates GAL4 activity through this phosphorylation in vivo. These results demonstrate a function for the SRB10/ CDK8 holoenzyme-associated CDK that involves regulation of transactivators by phosphorylation during transcriptional activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cyclin-Dependent Kinase 8
  • Cyclin-Dependent Kinases / metabolism*
  • DNA-Binding Proteins / metabolism
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Gene Expression Regulation, Enzymologic
  • Gene Expression Regulation, Fungal
  • In Vitro Techniques
  • Mice
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / metabolism*
  • RNA Polymerase II / metabolism*
  • Saccharomyces cerevisiae Proteins*
  • Transcription Factors / metabolism*
  • Transcriptional Activation / physiology
  • Yeasts / enzymology
  • Yeasts / genetics*


  • DNA-Binding Proteins
  • Fungal Proteins
  • GAL4 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • Protein-Serine-Threonine Kinases
  • Cyclin-Dependent Kinase 8
  • Cyclin-Dependent Kinases
  • SSN3 protein, S cerevisiae
  • RNA Polymerase II