The Hsp70 molecular chaperone machines

Members of the Hsp70 family form a central hub of the molecular chaperone network, controlling protein homeostasis in prokaryotes and in the ATP-containing compartments of eukaryotic cells. The heat-inducible form Hsp70, its constitutive cytosolic cognate Hsc70, the endoplasmic reticulum form BiP, and the mitochondrial form mHsp70/Mortalin, as well as the more distant Hsp70-related Hsp110s make up 1-2 % of the total mass of soluble proteins in human cells. They can use the energy of ATP-hydrolysis to prevent and forcefully revert the process of polypeptide misfolding and aggregation during and following stress, working as unfoldases to lift aberrant conformers out of kinetic traps. As such, Hsp70s, acting in cooperation with their J-domain co-chaperones and nucleotide exchange factors, constitute a central cellular defense system against cytotoxic misfolded protein conformers that may cause the onset of degenerative diseases, such as Parkinson, Alzheimer, diabetes and aging in general.

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