Open AccessInteraction of hsp70 with unfolded proteins: effects of temperature and nucleotides on the kinetics of binding.
Author(s) -
Daniel R. Palleros,
William J. Welch,
Anthony L. Fink
Publication year - 1991
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.88.13.5719
Subject(s) - hsp70 , nucleotide , circular dichroism , chemistry , cytosol , biophysics , kinetics , plasma protein binding , chaperone (clinical) , adenosine triphosphate , biochemistry , heat shock protein , biology , enzyme , physics , quantum mechanics , gene , medicine , pathology
Circular dichroism and HPLC gel filtration were used to show that cytosolic hsp70 is thermally stable but undergoes a conformational transition (midpoint, 43 degrees C; 57 degrees C in the presence of ATP or ADP) leading to oligomerization. hsp70 binds to unfolded, but not to folded, proteins in a temperature-dependent manner; complex formation is significant only at physiologically relevant temperatures. hsp70 binds ADP more tightly than ATP to form a binary complex, which binds to the unfolded protein more rapidly than free hsp70. ADP also inhibits the ATP-induced dissociation of the hsp70-protein complex. A regulatory role for the hsp70-nucleotide binary complexes is proposed.