Table 1.

Different types of heat shock transcription factors (HSFs), their localization and functions.

HSFs	Organism, and Homology	Oligomeric State, and Localization	Activators	Characterization	References
HSF1	Humans, mice, and chickens, 92% homology	Monomer (70 kDa), trimer (178 kDa), cyto-nuclear	Heat, metals, amino acid analogs	Constitutive and inducible, phosphorylation and developmental	[2,34]
HSF2	Humans, mice, and chickens, 92% homology	Dimer (127 kDa), trimer (202 kDa), cyto-nuclear	Hemin, embryogenesis	Activated during early blastocyst stage, limb buds, neuronal cells, and spermatogenesis	[2,20,35]
HSF3	Chickens and birds	Dimer, cytosol and nuclear	Heat, metals	Interact with cMyb and G1/S transition in cell cycle	[2,10,36]
HSF4 (a/b)	Humans	Trimer, constitutive, nuclear	Development	Active during lens development	[2,37,38]