A heat shock protein (HSP) is a group of proteins which increase their expression when the cells which contain them are exposed to elevated temperatures. This increase in expression is transcriptionally regulated. This dramatic upregulation of the heat shock proteins is a key part of the heat shock response. Production of high levels of heat shock proteins can also be triggered by exposure to different kinds of environmental stress conditions, such as infection, inflammation, exposure of the cell to toxins (ethanol, arsenic, trace metals and ultraviolet light, among many others), starvation, or hypoxia (oxygen deprivation). Consequently, the heat shock proteins are also referred to as stress proteins and their upregulation is sometimes described more generally as part of the stress response. A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Cells in culture, stained for keratin (red) and DNA (green) The cell is the structural and functional unit of all living organisms, sometimes called the building blocks of life. ... Transcription is the process through which a DNA sequence is enzymatically copied by an RNA polymerase to produce a complementary RNA. In the case of protein-encoding DNA, transcription is the beginning of the process that ultimately leads to the translation of the genetic code (via the mRNA intermediate) into... Stress tensor In physics, stress is the internal distribution of forces within a body that balance and react to the loads applied to it. ... An infection is the detrimental colonization of a host organism by a foreign species. ... Inflammation is the first response of the immune system to infection or irritation and may be referred to as the innate cascade. ... Ethyl alcohol, also known as ethanol or grain alcohol, is a flammable, colorless chemical compound, one of the alcohols that is most often found in alcoholic beverages. ... General Name, Symbol, Number arsenic, As, 33 Chemical series metalloids Group, Period, Block 15, 4, p Appearance metallic gray Atomic mass 74. ... Trace metals are metals in extremely small quantities, almost at the molecular level, that reside in or are present in animal and plant cells and tissue. ... Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. ... Starvation is a severe reduction in vitamin, nutrient, and energy intake, and is the most extreme form of malnutrition. ... Hypoxia is a pathological condition in which the body as a whole (generalized hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ...

Scientists have not discovered exactly how heat-shock (or other environmental stressors) activates the heat-shock factor. However, some studies suggest that an increase in damaged or abnormal proteins brings HSPs into action.

Heat-shock proteins (otherwise known as HSPs or stress proteins) are present in all cells at all biological levels. They appear when the cell is under heat stress (or other stress). Heat-shock proteins also occur under non-stressful conditions, simply "monitoring" the cell's proteins. Some examples of their role as "monitors" are that they carry old proteins to the cell's "recycling bin" and they help newly synthesised proteins fold properly. These activities are part of a cell's own repair system, called the "cellular stress response" or the "heat-shock response." The function of heat-shock proteins is similar in virtually all living organisms, from bacteria to humans. Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Binomial name Homo sapiens Linnaeus, 1758 Subspecies Homo sapiens idaltu (extinct) Homo sapiens sapiens Human beings define themselves in biological, social, and spiritual terms. ...

Heat shock proteins are molecular chaperones for protein molecules. They are usually cytoplasmic proteins and they perform functions in various intra-cellular processes. They play an important role in protein-protein interactions such as folding and assisting in the establishment of proper protein conformation (shape) and prevention of unwanted protein aggregation. By helping to stabilize partially unfolded proteins, HSPs aid in the transportation proteins across membranes within the cell. Some members of the HSP family are expressed at low to moderate levels in all organisms because of their essential role in protein maintenance. In biology, chaperones are proteins whose function is to assist other proteins in achieving proper folding. ... In chemistry, the conformation of a molecule is its spatial configuration. ...

The HSPs are named according to their molecular weights, for example Hsp70 and Hsp90 each define families of chaperones. The major classes of heat shock proteins are tabulated below. Hsp70 is a family of heat shock proteins including HSP70 (also known as Hsp72), Bip and the prokaryotic protein DnaK with an approximate molecular weight of 70 kDa. ... The molecular chaperone Hsp90 is one of the most abundant proteins in unstressed cells. ...

Potential applications

Heat-shock proteins are of potential interest to cancer researchers, based on research that has shown that animals may respond to cancer "vaccinations." Tumor cells were "attenuated" (or weakened) and injected in small quantities into a rodent, causing the rodent to become immune to future full-fledged tumor-cell injections. While any relevance of animal research to humans has not been established, it is possible that the same may hold true for other species. When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ... See the article about cancer for the main article about malignant tumors. ...

Some physicians are conducting research on using heat shock proteins in the treatment of cancer. Some researchers speculate that HSPs may be involved in binding protein fragments from dead malignant cells and presenting them to the immune system. When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ...

Researchers

Many years after the tumor cell attenuation research was done, Pramod Srivastava discovered that the specific part of the cell that was protecting the "immune" mice was the heat-shock proteins. See the article about cancer for the main article about malignant tumors. ...

Susan Lindquist is currently a leading heat-shock protein researcher. She is investigating, among other things, "how HSPs are regulated, and how they function to protect organisms from death and from developmental anomalies induced by heat." - from her faculty page at: http://ben-may.bsd.uchicago.edu/CCB/faculty/lindquist.html Susan Lindquist is a well-known molecular biologist studying (among other things) the effects of protein folding and heat-shock proteins. ...

Chaperones and heat shock proteins

Although the most important members of each family are tabulated here, it should be noted that some species may express additional chaperones, co-chaperones, and heat shock proteins not listed. Additionally, many of these proteins may have multiple splice variants (Hsp90α and Hsp90β, for instance) or conflicts of nomenclature (Hsp72 is sometimes called Hsp70). In genetics, splicing is a modification of genetic information prior to translation. ...