Assisting spontaneity: the role of Hsp90 and small Hsps as molecular chaperones

Hsp90 and small Hsps are two abundant types of eukaryotic stress protein whose function has remained largely enigmatic. In the cell, Hsp90 exists in a complex (with other Hsps and prolyl isomerases) possibly implicated in interactions with non-native proteins. Recent biochemical analysis of both Hsp90 and small Hsps has revealed that they may act as ATP-independent molecular chaperones involved in protein folding and unfolding events.