molecular chaperone

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molecular chaperone Any of a group of proteins in living cells that assist newly synthesized or denatured proteins to fold into their functional three-dimensional structures. The chaperones bind to the protein and prevent improper interactions within the polypeptide chain, so that it assumes the correct folded orientation. This process requires energy in the form of ATP. One class of chaperones, called chaperonins, occur in E. coli, chloroplasts, and mitochondria. They are heat-shock proteins, manufactured in response to raised temperature, and are presumed to help protect the cell from damage by refolding proteins that have been partially denatured by heat.