Serine palmitoyltransferase, the first enzyme in ceramide biosynthesis, is required for resistance to heat shock. We show that increased heat shock sensitivity in the absence of serine palmitoyltransferase activity correlates with a lack of induction of the major heat shock proteins (Hsps) at high temperature. Normal heat shock resistance can be restored, without restoration of ceramide synthesis or induction of Hsps, by overexpression of ubiquitin. This function of ubiquitin requires the proteasome. These data imply that the essential function of Hsp induction is the removal of misfolded or aggregated proteins, not their refolding. This suggests that cells stressed by heat shock do not die because of the loss of protein activity due to their denaturation, but because of the inherent toxicity of the denatured and/or aggregated proteins.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|