Open AccessDissociation of glucose-regulated protein Grp78 and Grp78-IgE Fc complexes by ATP.
Author(s) -
Héctor Toledo,
Anthony Carlino,
Vincent Vidal,
Betty Redfield,
Mig Y. Nettleton,
Jarema Kochan,
Nathan Brot,
Herbert Weissbach
Publication year - 1993
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.90.6.2505
Subject(s) - dimer , endoplasmic reticulum , monomer , biochemistry , chemistry , glucose regulated protein , dissociation (chemistry) , gtp' , recombinant dna , immunoglobulin e , biophysics , biology , unfolded protein response , enzyme , antibody , immunology , organic chemistry , gene , polymer
Recent studies have shown that ATP can dissociate dimers of the glucose-regulated protein Grp78 to monomers. In the present study, we have used purified recombinant Grp78 from Escherichia coli to investigate this reaction in more detail. During the course of the Grp78 dimer-monomer conversion, a stable Grp78 monomer-ATP complex is formed. Upon removal of the ATP, the Grp78 dimer is reformed. ADP, nonhydrolyzable ATP analogues, and GTP do not effect the dissociation of Grp78 dimers. A cell line that overproduces IgE Fc has been used to examine the nature of the Grp78-IgE Fc complexes present and the effect of ATP on them. Grp78-IgE Fc complexes ranging from 100 kDa to 300 kDa were observed by sucrose gradient analysis, suggesting that aggregate forms of Grp78 may be present in some of these complexes. Treatment of the extracts with ATP resulted in release of a Grp78 monomer from the complex. These results suggest that the dissociation of Grp78 oligomers by ATP may be involved in the function of Grp78 in protein translocation through the endoplasmic reticulum.