Identification of residues on Hsp70 and Hsp90 ubiquitinated by the cochaperone CHIP.

ABSTRACT: Molecular chaperones Hsp70 and Hsp90 are in part responsible for maintaining the viability of cells by facilitating the folding and maturation process of many essential client proteins. The ubiquitin ligase C-terminus of Hsc70 interacting protein (CHIP) has been shown in vitro and in vivo to associate with Hsp70 and Hsp90 and ubiquitinate them, thus targeting them to the proteasome for degradation. Here, we study one facet of this CHIP-mediated turnover by determining the lysine residues on human Hsp70 and Hsp90 ubiquitinated by CHIP. We performed in vitro ubiquitination reactions of the chaperones using purified components and analyzed the samples by tandem mass spectrometry to identify modified lysine residues. Six such ubiquitination sites were identified on Hsp70 (K325, K451, K524, K52

SUBMITTER: Kundrat L 

PROVIDER: S-EPMC2917188 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature