The binding activity of the heat shock transcription factor (HSF) to the heat shock element (HSE) is observed in non-stressed liver and freshly isolated hepatocytes when the expression of hsp70 is undetectable. HSF binding activity in non-stressed liver/hepatocytes is specific for HSE and similar to the HSF binding activity observed in heat shocked hepatocytes that is associated with hsp70 transcription. However, the HSF binding activity in non-stressed and heat shock cells can be distinguished on the basis of the thermal stability in vitro. The HSE binding activity of cell extracts isolated from non-stressed liver/hepatocytes was lost rapidly when the extracts were incubated at 37°C. In contrast, the HSF binding activity of cell extracts isolated from heat shocked hepatocytes was relatively stable at 37°C. Based on our observations, we propose that the activation of HSF is a multistep process that involves a change in conformation after oligomerization and the acquisition of DNA binding to a form that is more thermostable and is associated with increased hsp70 transcription.
|Original language||English (US)|
|Number of pages||7|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - Jun 15 1994|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology