Heat shock transcription factor and DNA. Molecular model of the binding domain region (blue) of a heat shock protein transcription factor bound to DNA (red, deoxyribonucleic acid). Transcription factors bind to DNA and help regulate the expression of the DNA's genetic information that is used to form proteins, in this case heat shock proteins (HSPs). HSPs are a group of proteins whose levels increase when cells are exposed to raised temperatures or other stress. The HSPs help reduce the impact of heat on cellular function. This example is from the Kluyveromyces lactis yeast.