Interaction of positive and negative regulatory proteins in the galactose regulon of yeast

Cell. 1987 Jul 3;50(1):143-6. doi: 10.1016/0092-8674(87)90671-4.


Transcriptional regulation in the galactose regulon of yeast is determined by an interplay between a positive regulatory protein, GAL4, and a negative regulatory protein, GAL80. We show that derivatives of GAL4 missing as few as 28 carboxy-terminal amino acids are not responsive to GAL80 regulation, implying that the carboxyl terminus of GAL4 is required for interaction with GAL80. Furthermore, a lesion in GAL4 that genetically defines the GAL80-interactive region maps to the 3' end of the gene. Since the carboxyl terminus of GAL4 has also been implicated in interaction with a transcriptional factor, we propose a model for negative regulation in which GAL80 and this factor compete for binding a common region of GAL4, and the on/off state of transcription is determined by the relative affinities of the negative regulator and the transcriptional factor for this region.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • DNA, Fungal / genetics
  • Galactose / genetics*
  • Gene Expression Regulation
  • Genes, Fungal*
  • Repressor Proteins / genetics*
  • Saccharomyces cerevisiae / genetics*
  • Structure-Activity Relationship
  • Transcription Factors / genetics*


  • DNA, Fungal
  • Repressor Proteins
  • Transcription Factors
  • Galactose