The two regions responsible for oligomerization between HSF1 monomers (the primary mediator of transcriptional responses to stress) are leucine zipper (LZ) domains 1-3, situated just downstream of the DBD, and 4, located between the RD and the C-terminal TAD.
The two regions responsible for oligomerization between HSF1 monomers are leucine zipper (LZ) domains 1-3 and 4 (these regions are also commonly referred to as HR-A/B and HR-C). LZ1-3 is situated just downstream of the DBD while LZ4 is located between the RD and the C-terminal TAD. HSF1 is highly conserved in eukaryotes and is the primary mediator of transcriptional responses to proteotoxic stress with important roles in non-stress regulation such as development and metabolism. 
