Heat shock proteins, protein folding role

Fig. 7.18. Role of heat shock proteins in folding. A. The Hsp70 family of proteins prevent folding of the nascent chain and promote unfolding. The ATPase domain of the protein has the actin fold. B. The Hsp60 class of protein has a barrel shape into which the protein fits. It acts as a template, binding and rebinding portions of the unfolded protein until folding is completed. It hydrolyzes many ATP bonds to provide energy for the process.

Pratt, W. The role of heat shock proteins in regulating the function, folding, and trafficking of the glucocorticoid receptor (1993) J.Biol.Chem. 268, 21455-21458... 

Heat shock proteins (HSPs) are a family of proteins expressed in almost all organisms from prokaryotes to humans. HSPs were originally described about four decades ago as proteins that were induced in the Drosophila melanogaster in response to a heat stress and hence derive the name HSR However, research over the years has uncovered these proteins to have a multitude of functions. Primarily, all HSPs act as molecular chaperons and assist in proper folding of naive proteins. Furthermore, HSPs have important roles in cellular processes including cell survival, inflammation, immunity, ion channel repair, and others. HSPs are also induced by a variety of stressors. Reactive oxygen species, cytotoxic injury, necrosis, ultraviolet radiation, metals, and many others are some examples. 

Ubiquitin, found in several cellular compartments (e.g., cytoplasm and the nucleus), belongs to a class of proteins referred to as stress proteins. Stress proteins, also called heat shock proteins (hsp), are so named because their syntheses are accelerated (and in some cases initiated) when cells encounter stress. (The name heat shock protein is misleading, because a variety of stressful conditions besides elevated temperature induce their synthesis.) Other stress proteins act as molecular chaperones, that is, they promote protein folding (p. 692). Heat shock proteins and molecular chaperones also play significant roles in protein transport and intermolecular interactions. 

Heat shock proteins (HSPs) are members of a family of molecular chaperones playing critical roles in protein folding, intracellular trafficking of proteins, and coping with proteins... 

Hubbard TJP, Sander C. The role of heat-shock and chaperone proteins in protein folding Possible molecular mechanisms. Protein Engineering 1991 4 711-7. 

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