NOTES/Ca²⁺ Is Essential for Multistep Activation of the Heat Shock Factor in Permeabilized Cells

Abstract

We have developed a novel permeabilized-cell system to study transcription mechanisms. In permeabilized cells, heat-induced activation of the heat shock factor and transcription of the hsp70 gene require Ca²⁺. Activation involves at least two steps: Ca²⁺- and heat-dependent activation of heat shock factor binding and a second step, prior to transcription of hsp70, that requires ATP and is sensitive to genistein, a protein kinase inhibitor.