Common characteristics of small dimeric chaperones

Abstract

Molecular chaperones constitute an important mechanism to prevent cell death caused by protein aggregation. ATP-independent chaperones are a group of low molecular weight proteins that can protect or restore the native structure of unfolded or mis-folded proteins without expenditure of energy. Because we recently found that the C-terminal domain of large-size subunit catalases has a chaperone activity, we are reviewing common characteristics of the most studied low molecular size chaperones, such as αB-crystalline, Hsp20, Spy, Hsp33 and Hsp31. We particularly examine the participation of hydrophobic and charged amino acid residues in protein substrate recognition and the role of dimer formation and its oligomerization in the molecular chaperone activity. We review for each of these molecular chaperones its protein structure, its cellular function and localization, and its importance for the cell.