Open AccessThe C‐terminal domain of human grp94 protects the catalytic subunit of protein kinase CK2 (CK2α) against thermal aggregation
Author(s) -
Roher Nerea,
Miró Francesc,
Boldyreff Brigitte,
Llorens Franc,
Plana Maria,
Issinger OlafGeorg,
Itarte Emilio
Publication year - 2001
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1033.2001.01905.x
Subject(s) - dithiothreitol , protein subunit , protein quaternary structure , chaperone (clinical) , chemistry , protein kinase a , biochemistry , fusion protein , monomer , cytosol , kinase , protein aggregation , enzyme , biophysics , recombinant dna , biology , organic chemistry , medicine , pathology , gene , polymer
The C‐terminal domain (residues 518–803) of the 94 kDa glucose regulated protein (grp94) was expressed in Escherichia coli as a fusion protein with a His 6 ‐N‐terminal tag (grp94‐CT). This truncated form of grp94 formed dimers and oligomers that could be dissociated into monomers by treatment with dithiothreitol. Grp94‐CT conferred protection against aggregation on the catalytic subunit of protein kinase CK2 (CK2α), although it did not protect against thermal inactivation. This anti‐aggregation effect of grp94‐CT was concentration dependent, with full protection achieved at grp94‐CT/CK2α molar ratios of 4 : 1. The presence of dithiothreitol markedly reduced the anti‐aggregation effects of grp94‐CT on CK2α without altering the solubility of the chaperone. It is concluded that the chaperone activity of the C‐terminal domain of human grp94 requires the maintenance of its quaternary structure (dimers and oligomers), which seems to be stabilised by disulphide bonds.