Hsp70-binding protein 1, also known as HSPBP1, belongs to a family of eukaryotic proteins identified as nucleotide exchange factors for HSP 70, which exhibit varying degrees of compartment and species specificity. It is localized primarily in cytoplasm and nucleus but is also found extracellularly. HspBP1 binds to HSP 70, inhibits its activity and promotes dissociation of nucleotides from the HSP 70 ATPase domain.