Small heat shock proteins (sHsps) have chaperone-like activity and can be found in almost all organisms. The most prominent sHsp is the vertebrate eye-lens protein α-crystallin. Typically, sHsps assemble into large, dynamic oligomers, which constantly exchange subunits. In vitro, they prevent the formation of insoluble aggregates of thermally or chemically denatured proteins. Since sHsps have no refolding activity, substrate proteins must be passed on to other chaperones in order to regain enzymatic activity. The dynamic nature of the sHsp complexes is critical for the interaction with substrate proteins. In this review, we reported on functional and structural properties of sHsps and the role these proteins play in the cellular chaperone network.
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