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.