Heat shock proteins (HSPs) are a class of functionally related proteins whose expression is increased when cells are exposed to elevated temperature or other stresses. HSPs are found in virtually all living organisms, from bacteria to humans. Heat shock proteins, as a class, are among the most highly expressed cellular proteins across all species. As their name implies, heat shock proteins protect cells when stressed by elevated temperatures. They account for 1-2% of total protein in unstressed cells. However when cells are heated, the fraction of heat shock proteins increases to 4-6% of cellular proteins. In eukaryotic organisms, the principal class of HSPs in human are HSP60, HSP70, HSP90 and HSP100. Another novel class HSP33 is also found exclusively, which interestingly absence in archaea or other eukaryotes. In plants, Hsps are greatly varied in level of expression as well as their type. The most prominent types are Hsp20, Hsp70, Hsp90 and Hsp100 according to well studied plant species Arabidopsis thaliana. Higher plants are characterized by the presence of at least 20 types of small sHsps, but one single species could contain 40 types of these sHsps. (Computational Approach to Search for Plant Homologues of Human Heat Shock Protein, Animesh Sarker)
Last date updated on April, 2024
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