Abstract
Recent studies have shown that the functions of PTH-related protein (PTHrP) and its derived peptides cannot be attributed solely to PTH/PTHrP receptor binding. The present study focused on the identification of other proteins that might bind PTHrP at the cell surface. Using affinity chromatography, we applied extracts of cell-surface biotinylated proteins from cancer and normal cell lines over Sepharose beads coupled with different PTHrP-derived peptides. Elution with the corresponding free peptide revealed a major protein of about 70 kDa that was present in all of the PTHrP peptide eluates from cancer cell extracts but not from normal breast cell extracts. Mass spectroscopy analysis and immunoblotting identified this PTHrP-binding protein as heat shock protein-70 (HSP70). Using a recently published algorithm that predicts HSP70 binding sites within proteins, we found that all four PTHrP peptides used in these studies contain amino acid motifs with high probabilities for HSP70 binding in vivo. Cell culture studies in the presence of a polyclonal anti-HSP70 antibody demonstrated increased PTHrP secretion, decreased total cellular protein, and differentially regulated proliferation. Taken together, these studies demonstrate a novel and biologically relevant interaction between cell surface-expressed HSP70 and PTHrP in cancer.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
