Some like it hot: The structure and function of small heat-shock proteins

Small heat-shock proteins (sHsps) are a widespread and diverse class of molecular chaperones. Recent evidence suggests that they maintain protein homeostasis by binding proteins in non-native conformations, thereby preventing substrate aggregation. Some members of the sHsp family are inactive or only partially active under physiological conditions, and transition toward the active state is induced by specific triggers, such as elevated temperature. Release of substrate proteins bound to sHsps requires cooperation with ATP-dependent chaperones, suggesting that sHsps create a reservoir of non-native proteins for subsequent refolding.