Hsp70-binding protein 1 (HSPBP1) is a member of a family of eukaryotic proteins identified as nucleotide exchange factors for HSP 70 that exhibit varying degrees of compartment and species specificity. HSPBP1 is localized mainly in cytoplasm and nucleus but is also found extracellularly. HSPBP1 is mostly expressed in heart and skeletal muscle .HSPBP1 binds to HSP 70, inhibits its activity and promotes dissociation of nucleotides from the HSP 70 ATPase domain. In addition, HSPBP1 inhibits HSPA1A chaperone activity by changing the conformation of the ATP-binding domain of HSPA1A and obstructing the ATP binding. HSPBP1 may also have a role in tumor (dys)regulation of chaperone proteins. Furthermore, HSPBP1 hinders ubiquitination mediated by STUB1 and inhibits chaperone-assisted degradation of immature CFTR Synonyms: Hsp70-binding protein 1, Heat shock protein-binding protein 1, Hsp70-interacting protein 1, Hsp70-binding protein 2, Hsp70-interacting protein 2, HspBP1, HspBP2, HSPBP1, HSPBP, FES1