Mildly acidic pH activates the extracellular molecular chaperone clusterin.

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Citation

Poon S, Rybchyn MS, Easterbrook-Smith SB, Carver JA, Pankhurst GJ, Wilson MR

Mildly acidic pH activates the extracellular molecular chaperone clusterin.

J Biol Chem. 2002 Oct 18;277(42):39532-40. Epub 2002 Aug 9.

PubMed ID
12176985 [ View in PubMed
]
Abstract

Many features of the chaperone action of clusterin are similar to those of the intracellular small heat shock proteins (sHSPs) that, like clusterin, exist in solution as heterogeneous aggregates. Increased temperature induces dissociation of some sHSP aggregates and an enhanced chaperone action, suggesting that a dissociated form is the active chaperone species. We recently reported that clusterin aggregates dissociate at mildly acidic pH. To further explore the similarities between clusterin and the sHSPs, we tested the effects of temperature and pH on the structure of clusterin and its chaperone action. Our results demonstrate that increased temperature does not induce dissociation of clusterin aggregates, or other major structural changes, and has little effect on its chaperone action. However, we show that the chaperone action of clusterin is enhanced at mildly acidic pH. Clusterin is the first chaperone shown to be activated by reduced pH. This unique mode of activation appears to result from an increase in regions of solvent-exposed hydrophobicity, which is independent of any major changes in secondary or tertiary structure. We propose a model in which low pH-induced dissociation of clusterin aggregates increases the abundance of the heterodimeric chaperone-active species, which has greater hydrophobicity exposed to solution.

DrugBank Data that Cites this Article

Polypeptides
NameUniProt ID
ClusterinP10909Details