Heat shock 70 kDa protein cognate 4 belongs to the heat shock protein 70 family, is homolous to Heat shock 70 kDa protein (Hsp70). Heat shock proteins are a family of proteins that are produced by cells in response to exposure to stressful conditions. Hsp70 Proteins are central components of the cellular network of molecular chaperones and folding catalysts. They assist a large variety of protein folding processes in the cell by transient association of their substrate binding domain with short hydrophobic peptide segments within their substrate proteins. The substrate binding and release cycle is driven by the switching of Hsp70 between the low-affinity ATP bound state and the high-affinity ADP bound state. Thus, ATP binding and hydrolysis are essential in vitro and in vivo for the chaperone activity of Hsp70 proteins.