HEAT-SHOCK FACTOR-I AND THE HEAT-SHOCK COGNATE-70 PROTEIN ASSOCIATE IN HIGH-MOLECULAR-WEIGHT COMPLEXES IN THE CYTOPLASM OF NIH-3T3 CELLS

Interaction of heat shock transcription factor-1 (HSF-1) with the seventy kilodalton heat shock cognate protein (HSC70) was examined in NIH 3T3 cells. HSF-1 was found in the cytoplasm of non-stressed cells associated with HSC70 in large (Mr 400-500,000) complexes. After heat shock, HSF-1 became concentrated in the nucleus in smaller, more stable complexes that did not contain HSC70, an indication of significant rearrangement within the complexes. These experiments show a profound effect of heat shock on the structure and stability of HSF-1 complexes during nuclear localization and support the hypothesis that HSC70 binding may control HSF-1 function. (C) 1995 Academic Press, Inc.