HSP70: Protein Type

Immunofluorescent detection of Hsp70 using Mouse Anti-HSP70 Monoclonal Antibody, Clone 2A4 in HeLa cells.
HSP70s are monomeric proteins that reside in the cytosol of prokaryotes and the cytosol, nuclei, ER, mitochondria and chloroplasts of eukaryotes 8. In addition to their intracellular location, HSP70s have been found in the plasma membrane of malignantly transformed cells, on virally / bacterially infected cells and in the extracellular space. Extracellular Hsp70 exists in a free soluble form, complexed to antigenic peptides, or in exosomes 12,13,14,15. Noteworthy, Hsp70-1 as the most prominent member of the HSP70 family can be detected in the plasma membrane of a large proportion of different tumor entities, but not in the plasma membrane of normal cells/tissues 16,17,18. Several observations have led to the hypothesis that in tumor cells Hsp70-1 is an integral membrane protein associated with certain membrane lipid components 15, 16.