Hsp70-protein complexes

Early attempts to determine the stoichiometry of hsp70-protein complexes by a correlation between Kj and log MM were unsuccessful because the substrate proteins are substantially unfolded in their complexes with hsp70. and hsp70s themselves probably deviate from a spherical shape to illustrate this point it should suffice to say that DnaK and DnaK-RCMLA complex behave as if they had apparent moleculcu masses of 93 and 156 kDa, respectively, when a correlation of log MM vs. Kd (using the same five standard proteins mentioned above plus bovine serum albumin dimer) was used to estimate moleculcir masses. 

Dittmar KD, Banach M, Galigniana MD, Pratt WB. (1998) The role of DNAJ-Kke proteins in glucocorticoid receptor.hsp90 heterocomplex assembly by the reconstituted hsp90.p60. hsp70 foldosome complex. J Biol Chem. 273, 7358-7366. 

Hsp70 proteins with their co-chaperones and cooperating chaperones thus constitute a complex network of folding machines. This chapter describes the molecular basis of this network. Particular emphasis is given to the DnaK system of Escherichia coli as it is the best understood Hsp70 system, and to the mechanistic differences between Hsp70 family members. 

Perdew, G.H. Whitelaw, M.L. (1991). Evidence that the 90 kD heat shock protein exists in cytosol in heteromeric complexes containing hsp70 and three other proteins with Mr of 63,000, 56,000, 50,000. J. Biol. Chem. 266,6708-6713. 

Sargent, C.A., Dunhan, 1., Trowsdale, J., Campbell, R.D. (1989). Human major histocompatibility complex contains genes for the major heat shock protein hsp70. Proc. Natl. Acad. Sci. USA 86, 1968-1972. 

---