On the substrate specificity of alpha-crystallin as a molecular chaperone.

alpha-Crystallin, the major protein of the ocular lens, acts as a molecular chaperone by preventing the thermal aggregation of proteins. However, in contrast with many other heat shock proteins, alpha-crystallin fails to protect proteins from aggregation during refolding reactions. Our results indicate that alpha-crystallin has substrate specificity different from other chaperones and recognizes specific non-native intermediates formed on the denaturation pathway only, with no affinity for intermediates formed on the refolding pathway.