Heat shock factor protein 1 is a protein that in humans is encoded by the HSF1 gene. HSF1 exists as an inactive monomer in a complex with Hsp40/Hsp70 and Hsp90. Upon stress, such as elevated temperature, HSF1 is released from the chaperone complex and trimerizes. HSF1's target genes include major inducible heat shock proteins such as Hsp72, and noncoding RNA within Satellite III repeat regions. Its attenuation phase is initiated as a negative feedback loop with its gene product Hsp70 binding to its transactivation domain.
