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Tuesday 20 April 2004

The heat-shock proteins (HSPs) belong to a larger group of polypeptides, the stress proteins, that are induced in various combinations in response to environmental challenges and developmental transitions. Synthesis of the small (27-kD) HSP has been shown to be correlated with the acquisition of thermotolerance.




All cells respond to stress such as elevated temperatures by making a distinct set of proteins known as the stress-related or heat-shock proteins (HSPs).

These proteins may play some protective role in cells exposed to stress such as elevated temperatures.

The heat-shock proteins can be grouped into 3 major classes based on their approximate molecular weights and degrees of homology.

One class comprises several relatively small proteins with molecular weights between 15,000 and 30,000 (small HSPs).

The most highly conserved class has molecular weights of approximately 70,000 (MIM.140550, MIM.140560, MIM.140570) (HSP70).

The third class comprises heat-shock proteins with molecular weights ranging between 80,000 and 90,000. This latter class, referred to as the HSP90 family, exists in multiple forms in mammalian cells. In humans, 2 distinct HSP90 cDNA clones were identified that hybrid-select different mRNA transcripts encoding 2 members of the HSP90 family. These were called HSP89-alpha and HSP89-beta.

See also

- Proteins