PROTEINS INTERACTING WITH THE MOLECULAR CHAPERONE HSP70 HSC70 - PHYSICAL ASSOCIATIONS AND EFFECTS ON REFOLDING ACTIVITY/

We investigated several hsp70/hsc70 interacting proteins and establish ed by two independent techniques that hsp40 and HOp/p60 specifically i nteract with the 257 residue carboxy-terminal domain of hsp70 while Ha p-46 and Hip/p48 bind the 383 residue amino-terminal ATP binding domai n. Hap-46 and Hip/p48 competed for binding to hsc70, while Hap-46 had no effect on the binding of either Hop/p60 or hsp40 to hsc70. Hap-46 i nhibited the refolding of thermally denatured firefly luciferase in an hsc70 and hsp40 dependent assay, and this effect was largely compensa ted by Hop/p60. These interacting proteins thus appear to cooperate in affecting the chaperoning activity of hsp70/hsc70. (C) 1997 Federatio n of European Biochemical Societies.