Antigen: purified recombinant GPR94 protein · Clone designation: 9G10 · Host: rat · Isotype: IgG2a · Application(s): WB. IP, and flow cytometry · Glucose regulated protein 94 (GRP94) is a constitutively expressed endoplasmic reticulum (ER) lumenal protein that is up-regulated in response to cellular stress such as heat shock, oxidative stress or glucose depletion. GRP94 is thought to play a role in protein translocation to the ER, in their subsequent folding and assembly, and in regulating protein secretion.¹ GRP94 also plays a role in antigen presentation by accessing the endogenous pathway and eliciting specific cytotoxic T lymphocyte (CTL) responses to chaperone bound peptides via the major histocompatibility complex (MHC) class I pathway.² GRP94 is a member of the Hsp90 family of stress proteins and shares sequence homology with its cytosolic equivalent, Hsp90.³ Both Hsp90 and GRP94 are calcium binding proteins.⁴ Despite sharing 50% sequence homology over its N domains and complete conservation in its ligand binding domains with Hsp90, GRP94, and Hsp90 differ in their interactions with regulatory ligands as GRP94 has weak ATP binding and hydrolysis activity.⁵ GRP94 exists as a homodimer and the two subunits interact at two distinct intermolecular sites, C-terminal dimerization domains and the N-terminal interacts with the middle domain of opposing subunits.⁶ GRP94 contains a carboxy terminal KDEL (Lys-Asp-Glu-Leu) sequence which is believed to aid in its retention in the ER.⁷

1 Ruddon, R.W., and Bedows, E. Assisted protein folding. J Biol Chem 272(6) 3125-3128 (1997).

2 Srivastava, P.K., Udono, H., Blachere, N.E., et al. Heat shock protein transfer peptides during antigen processing and CTL priming. Immunogenetics 39(2) 93-98 (1994).

3 Mazzarella, R.A., and Green, M. ERp99, an abundant, conserved glycoprotein of the endoplasmic reticulum, is homologous to the 90-kDa heat shock protein (hsp90) and the 94-kDa glucose regulated protein (GRP94). J Biol Chem 262(18) 8875-8883 (1987).

4 Kang, H.S., and Welch, W.J. Characterization and purification of the 94-kDa glucose-regulated protein. J Biol Chem 266(9) 5643-5649 (1991).

5 Soldano, K.L., Jivan, A., Nicchitta, C.V., et al. Structure of the N-terminal domain of GRP94. Basis for ligand specificity and regulation. J Biol Chem 278(48) 48330-48338 (2003).

6 Chu, F., Maynard, J.C., Chiosis, G., et al. Identification of novel quaternary domain interactions in the Hsp90 chaperone, GRP94. Protein Sci 15 1260-1269 (2006).

7 Peter, F., Van, P.N., and Söling, H. Different sorting of Lys-Asp-Glu-Leu proteins in rat liver. J Biol Chem 267(15) 10631-10637 (1992).

Sato, K., Torimoto, Y., Tamura, Y., et al. Immunotherapy using heat-shock protein preparations of leukemia cells after syngeneic bone marrow transplantation in mice. Blood 98 1852-1857 (2001).

Hoshino, T., Wang, J., Devetten, M.P., et al. Molecular chaperone GRP94 binds to the fanconi anemia group C protein and regulates its intracellular expression. Blood 91(11) 4379-4386 (1998).

Gusarova, V., Caplan, A.J., Brodsky, J.L., et al. Apoprotein B degradation is promoted by the molecular chaperones hsp90 and hsp70. J Biol Chem 276(27) 24891-24900 (2001).

Srivastava, P.K., Udono, H., Blachere, N.E., et al. Heat shock protein transfer peptides during antigen processing and CTL priming. Immunogenetics 39(2) 93-98 (1994).

Chu, F., Maynard, J.C., Chiosis, G., et al. Identification of novel quaternary domain interactions in the Hsp90 chaperone, GRP94. Protein Sci 15 1260-1269 (2006).

Soldano, K.L., Jivan, A., Nicchitta, C.V., et al. Structure of the N-terminal domain of GRP94. Basis for ligand specificity and regulation. J Biol Chem 278(48) 48330-48338 (2003).

Kang, H.S., and Welch, W.J. Characterization and purification of the 94-kDa glucose-regulated protein. J Biol Chem 266(9) 5643-5649 (1991).

Mazzarella, R.A., and Green, M. ERp99, an abundant, conserved glycoprotein of the endoplasmic reticulum, is homologous to the 90-kDa heat shock protein (hsp90) and the 94-kDa glucose regulated protein (GRP94). J Biol Chem 262(18) 8875-8883 (1987).

Ruddon, R.W., and Bedows, E. Assisted protein folding. J Biol Chem 272(6) 3125-3128 (1997).

Riera, M., Roher, N., Miró, F., et al. Association of protein CK2 with eukaryotic translation initiation factor eIF-2 and with grp94/endoplasmin. Mol Cell Biochem 191(1-2) 97-104 (1999).

Choukhi, A., Ung, S., Wychowski, C., et al. Involvement of endoplasmic reticulum chaperones in the folding of hepatitis C virus glycoproteins. J Virol 72(5) 3851-3858 (1998).

Allen, S., Abuzenadah, A.M., Hinks, J., et al. A novel von Willebrand disease-causing mutation (Arg273Trp) in the von Willebrand factor propeptide that results in defective multimerization and secretion. Blood 96 560-568 (2000).

Yun, S., Gärtner, U., Arendt, T., et al. Increase in vulnerability of middle-aged rat brain to lead by cerebral energy depletion. Brain Res Bull 52(5) 371-378 (2000).

Peter, F., Van, P.N., and Söling, H. Different sorting of Lys-Asp-Glu-Leu proteins in rat liver. J Biol Chem 267(15) 10631-10637 (1992).

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