The Gal4 activation domain binds Sug2 protein, a proteasome component, in vivo and in vitro

J Biol Chem. 2001 Aug 17;276(33):30956-63. doi: 10.1074/jbc.M102254200. Epub 2001 Jun 19.


An in vivo protein interaction assay was used to search a yeast cDNA library for proteins that bind to the acidic activation domain (AD) of the yeast Gal4 protein. Sug2 protein, a component of the 19 S regulatory particle of the 26 S proteasome, was one of seven proteins identified in this screen. In vitro binding assays confirm a direct interaction between these proteins. SUG2 and SUG1, another 19 S component, were originally discovered as a mutation able to suppress the phenotype of a Gal4 truncation mutant (Gal4(D)p) lacking much of its AD. Sug1p has previously been shown to bind the Gal4 AD in vitro. Taken together, these genetic and biochemical data suggest a biologically significant interaction between the Gal4 protein and the 19 S regulatory particle of the proteasome. Indeed, it is demonstrated here that the Gal4 AD interacts specifically with immunopurified 19 S complex. The proteasome regulatory particle has been shown recently to play a direct role in RNA polymerase II transcription and the activator-19 S interaction could be important in recruiting this large complex to transcriptionally active GAL genes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphatases / metabolism*
  • Animals
  • Benzamides
  • Binding Sites
  • Cysteine Endopeptidases / metabolism
  • DNA-Binding Proteins
  • Dimerization
  • Fungal Proteins / chemistry
  • Fungal Proteins / metabolism*
  • Multienzyme Complexes / metabolism
  • Promoter Regions, Genetic
  • Proteasome Endopeptidase Complex
  • Rabbits
  • Saccharomyces cerevisiae Proteins*
  • Transcription Factors / chemistry
  • Transcription Factors / metabolism*
  • Tyrosine / analogs & derivatives
  • Tyrosine / genetics


  • Benzamides
  • DNA-Binding Proteins
  • Fungal Proteins
  • GAL4 protein, S cerevisiae
  • Multienzyme Complexes
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • Tyrosine
  • 1-nitrohydroxyphenyl-N-benzoylalanine
  • Cysteine Endopeptidases
  • Proteasome Endopeptidase Complex
  • Adenosine Triphosphatases
  • RPT4 protein, S cerevisiae