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Chaperonin GroEL- resisting heat shock at any temperature

Laura Greeley

Laura Greeley I'm on ScienceSeeker-Microscope

Heat shock is the effect of subjecting a cell to a higher temperature than that of the ideal metabolic temperature of the organism. One of the most typical responses of the cells is transcriptional up-regulation of genes encoding heat shock proteins, or the increased production of the precursor of heat shock proteins. Heat shock proteins help cells to combat an array of problem when they are under stress. One subgroup of heat shock proteins is responsible for helping proteins to maintain or regain their shape and thereby function, and are known as chaperonin. One of the most thoroughly studied chaperonins is GroEL.

GroEL assists ATP-dependent folding of many proteins by binding one of the unfolded proteins in an open ring through multiple hydrophobic contacts with the apical domains serving to prevent misfolding and aggregation (precipitation). This is important to cell survival because not only are misfolded (misshapen) proteins nonfunctional but aggregated proteins are often toxic to the cell. GroEL protects unfolded proteins by binding the target protein and then a co-chaperonin GroES and ATP with the same ring.  This complex encapsulates smaller proteins (<60 kDa) and folding is initiated.  After ATP hydrolysis, both GroES and the polypeptide are released and the cycle can repeat until the protein is refolded.

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