The 70 kilodalton heat shock proteins (Hsp70s) are a family of conserved ubiquitously expressed heat shock proteins. The Hsp70s are an important part of the cells machinery for protein folding, and help to protect cells from stress. Hsp70, which exhibits both cytoprotectant and immunoregulatory functions. Members of the Hsp70 family are strongly upregulated by heat stress and toxic chemicals, particularly heavy metals such as arsenic, cadmium, copper, mercury, etc. Arabidopsis plants contain two genes coding for mitochondrial Hsp70-type chaperon-like proteins, AtHscA1 (At4g37910) and AtHscA2 (At5g09590) .
