Figure 4.

HSF mobility and association with hsp70 vary with the physiological state of the cells. (A) Duration of heat shock. Cells were grown at 20°C and then shifted to 41°C. At the indicated times, samples were harvested, and extracts were prepared. Samples were analyzed by gel mobility shift DNA-binding assay, either with (left 4 lanes) or without (right 4 lanes) the addition of 1 mM ATP. (B) Steady-state growth conditions. Cells were grown at 25°C in media containing the indicated concentrations of glucose, and extracts were prepared. For comparison, cells grown in standard 2% glucose medium were either heat shocked (hs) or left as unshocked controls (c). Gel mobility shift DNA-binding assays were performed, either with (+) or without (−) the addition of ATP. (C) Quantitation (by phosphorimager) of the gel shown in B.