HSP60: Introduction

The 60 kDa heat shock protein 60 (Hsp60), also known as 60 kDa chaperonin (Cpn60) 1, represents one of the most conserved proteins in living organisms and is present in all three “primary kingdoms” of life: eukaryotes, eubacteria, and Archaea. HSP60 chaperones can be found not only in the cytosol, chloroplasts, hydrogenosomes and mitochondria 2 but also on the cell surface and in the extracellular milieu 3 where they serve as danger signals of stressed or damaged cells and act as potent stimulators of immune responses 4,5. HSP60s interact with many polypeptides in an ATP-dependent manner and possess a peptide-dependent ATPase activity 6. The Escherichia coli Hsp60 (GroEL) is the best studied representative of the huge HSP60/CPN60 family whose expression is strongly induced upon heat shock. Together with its co-chaperone, GroES (Hsp10), GroEL assists the correct folding of nascent polypeptides and the recycling of misfolded proteins 7,8. Hsp60 levels gradually increase or decrease during carcinogenesis in various organs and thus might serve as a prognostic or diagnostic marker in certain cancers 9.