Antigen: human Hsp73 amino acids 650-670 · Host: rabbit · Application(s): WB, IP, and IF · Hsp70 genes encode abundant heat-inducible 70 kDa Hsps (Hsp70s). In most eukaryotes Hsp70 genes exist as part of a multigene family. They are found in most cellular compartments of eukaryotes including nuclei, mitochondria, chloroplasts, the endoplasmic reticulum and the cytosol, as well as in bacteria. The genes show a high degree of conservation, having at least 50% identity.¹ The N-terminal two thirds of Hsp70s are more conserved than the C-terminal third. Hsp70 binds ATP with high affinity and possesses a weak ATPase activity which can be stimulated by binding to unfolded proteins and synthetic peptides.² When Hsc70 (constitutively expressed) present in mammalian cells was truncated, ATP binding activity was found to reside in an N-terminal fragment of 44 kDa which lacked peptide binding capacity. Polypeptide binding ability therefore resided within the C-terminal half.³ The structure of this ATP binding domain displays multiple features of nucleotide binding proteins.⁴ When cells are subjected to metabolic stress (e.g., heat shock) a member of the Hsp70 family, Hsp70 (Hsp72), is expressed; Hsp70 is highly related to Hsc70 (>90% sequence identity). Constitutively expressed Hsc70 rapidly forms a stable complex with the highly inducible Hsp70 in cells following heat shock. The interaction of Hsc70 with Hsp70 is regulated by ATP. These two heat shock proteins move together in the cell experiencing stress. Furthermore, research on Hsc70 implicates it with a role in facilitating the recovery of centrosomal structure and function after heat shock.⁵

1 Boorstein, W.R., Ziegelhoffer, T., and Craig, E.A. Molecular evolution of the HSP70 multigene family. J Mol Evol 38(1) 1-17 (1994).

2 Rothman, J.E. Polypeptide chain binding proteins: Catalysts of protein folding and related processes in cells. Cell 59 591-601 (1989).

3 DeLuca-Flaherty, C., McKay, D.B., Parham, P., et al. Uncoating protein (hsc70) binds a conformationally labile domain of clathrin light chain LCa to stimulate ATP hydrolysis. Cell 62 875-887 (1990).

4 Bork, P., Sander, C., and Valencia, A. An ATPase domain common to prokaryotic cell cycle proteins, sugar kinases, actin, and hsp70 heat shock proteins. Proc Natl Acad Sci USA 89 7290-7294 (1992).

5 Brown, C.R., Hong-Brown, L.Q., Doxsey, S.J., et al. Molecular chaperones and the centrosome. A role for Hsp 73 in centrosomal repair following heat shock treatment. J Biol Chem 271(2) 833-840 (1996).

Brown, C.R., Martin, R.L., Hansen, W.J., et al. The constitutive and stress inducible forms of hsp 70 exhibit functional similarities and interact with one another in an ATP-dependent fashion. J Cell Biol 120(5) 1101-1112 (1993).

Rothman, J.E. Polypeptide chain binding proteins: Catalysts of protein folding and related processes in cells. Cell 59 591-601 (1989).

Brown, C.R., Hong-Brown, L.Q., Doxsey, S.J., et al. Molecular chaperones and the centrosome. A role for Hsp 73 in centrosomal repair following heat shock treatment. J Biol Chem 271(2) 833-840 (1996).

Bork, P., Sander, C., and Valencia, A. An ATPase domain common to prokaryotic cell cycle proteins, sugar kinases, actin, and hsp70 heat shock proteins. Proc Natl Acad Sci USA 89 7290-7294 (1992).

DeLuca-Flaherty, C., McKay, D.B., Parham, P., et al. Uncoating protein (hsc70) binds a conformationally labile domain of clathrin light chain LCa to stimulate ATP hydrolysis. Cell 62 875-887 (1990).

Boorstein, W.R., Ziegelhoffer, T., and Craig, E.A. Molecular evolution of the HSP70 multigene family. J Mol Evol 38(1) 1-17 (1994).

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