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nucleotide exchange factor GrpE GrpE is the adenine nucleotide exchange factor of DnaK (Hsp70)-type ATPases. In bacteria, the DnaK-DnaJ-GrpE (KJE) chaperone system functions at the fulcrum of protein homeostasis. GrpE participates actively in response to heat shock by preventing aggregation of stress-denatured proteins; unfolded proteins initially bind to DnaJ, the J-domain ATPase-activating protein (Hsp40 family), whereupon DnaK hydrolyzes its bound ATP, resulting in a stable complex. The GrpE dimer binds to the ATPase domain of Hsp70 catalyzing the dissociation of ADP, which enables rebinding of ATP, one step in the Hsp70 reaction cycle in protein folding. In eukaryotes, only the mitochondrial Hsp70, not the cytosolic form, is GrpE dependent. Over-expression of Hsp70 molecular chaperones is important in suppressing toxicity of aberrantly folded proteins that occur in Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis, as well as several polyQ-diseases such as Huntington's disease and ataxias. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",