The 70 kilodalton heat shock proteins (Hsp70s) are a family of conserved ubiquitously expressed heat shock proteins. Proteins with similar structure exist in virtually all living organisms. The Hsp70s are an important part of the cell’s machinery for protein folding, and help to protect cells from stress.

When not interacting with a substrate peptide, Hsp70 is usually in an ATP bound state. By binding tightly to partially synthesized peptide sequences (incomplete proteins), Hsp70 prevents them from aggregating and being rendered nonfunctional. Hsp70 proteins can act to protect cells from thermal or oxidative stress. Hsp70 also aids in transmembrane transport of proteins, by stabilizing them in a partially folded state. Finally, in addition to improving overall protein integrity, Hsp 70 directly inhibits apoptosis.