DnaK is the prokaryotic analogue of eukaryotic Hsp70. Heat shock proteins applies to a group of proteins that assist in the assembly, folding, and translocation of other proteins. In addition, they protect the cell against heat injury or other forms of stress. All cells, prokaryotic and eukaryotic, are able to respond to different cellular stresses by synthesizing these proteins. Heat shock proteins are highly conserved, ubiquitously distributed, and involved in important aspects of viral and bacterial infections, autoimmune diseases, and in cancer immunity.
Two families of molecular chaperones have been identified. The members of the Hsp70 family (DnaK/DnaJ/GrpE) bind to the growing polypeptide chain and prevent its premature folding. The chaperonin family (GroEL and GroES) assists in correct folding when the complete polypeptide chain is formed and is transported into the cytosol or mitochondria. All the major heat shock proteins help to suppress irreversible unfolding reactions. These protein folding 'assistants' may have important functions in amyloid diseases where incorrectly folded proteins accumulate as folded aggregates.