Saccharomyces cerevisiae IRE2/HAC1 is involved in IRE1-mediated KAR2 expression

Nucleic Acids Res. 1996 Nov 1;24(21):4222-6. doi: 10.1093/nar/24.21.4222.


The Saccharomyces cerevisiae IRE1 gene, encoding a putative receptor-type protein kinase, is known to be required for inositol prototrophy and for the induction of a chaperon molecule, BiP, encoded by KAR2, under stress conditions such as tunicamycin addition. We have characterized a yeast gene, IRE2, which was isolated as a suppressor gene that complements the inositol auxotrophic phenotype of the ire1 mutation. Sequencing analysis revealed that IRE2 is identical to HAC1, which encodes a transcription factor having a basic-leucine zipper motif. Introduction of IRE2/HAC1 into the ire1 mutant clearly restored the expression of KAR2 upon tunicamycin treatment. ire2/hac1-disrupted yeast cells showed not only the inositol auxotrophic phenotype but also the tunicamycin sensitivity, and failed to induce the expression of KAR2. These results clearly indicate that the IRE2/HAC1 gene product plays a critical role in the induction of KAR2 expression and in the inositol prototrophy mediated by IRE1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Basic-Leucine Zipper Transcription Factors
  • Dimerization
  • Escherichia coli
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism*
  • Gene Expression Regulation, Fungal
  • HSP70 Heat-Shock Proteins / genetics*
  • Membrane Glycoproteins / metabolism*
  • Molecular Sequence Data
  • Mutagenesis
  • Protein-Serine-Threonine Kinases*
  • Repressor Proteins / metabolism*
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins*
  • Transcription Factors*
  • Tunicamycin / pharmacology


  • Anti-Bacterial Agents
  • Basic-Leucine Zipper Transcription Factors
  • Fungal Proteins
  • HAC1 protein, S cerevisiae
  • HSP70 Heat-Shock Proteins
  • KAR2 protein, yeast
  • Membrane Glycoproteins
  • Repressor Proteins
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • Tunicamycin
  • IRE1 protein, S cerevisiae
  • Protein-Serine-Threonine Kinases

Associated data

  • GENBANK/D26506