The endoplasmic reticulum stress protein GRP94, in addition to BiP, associates with unassembled immunoglobulin chains.
The molecular chaperone BiP/GRP78 associates with various polypeptides in the endoplasmic reticulum, including immunoglobulin chains. We now show, using chemical cross-linking, that another endoplasmic reticulum stress protein, GRP94, associates with newly synthesized immunoglobulin light and heavy chains. We demonstrate the presence of ternary complexes composed of immunoglobulin chains, BiP and GRP94. Because both BiP and GRP94 associate far less with fully assembled immunoglobulin than with unassembled subunits, our data suggest that GRP94, like BiP, functions as a molecular chaperone. The presence of both BiP and GRP94 in the same complex further suggests that the two stress proteins work in concert during the folding and assembly of immunoglobulins.
Melnick
J
J
Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710.
Aviel
S
S
Argon
Y
Y
D002352:Carrier Proteins / Q000378:metabolism*; D003432:Cross-Linking Reagents; D004591:Electrophoresis, Polyacrylamide Gel; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism*; D007136:Immunoglobulins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D018832:Molecular Chaperones; D009154:Mutation; D010957:Plasmids; D011233:Precipitin Tests; D014407:Tumor Cells, Cultured
D002352:Carrier Proteins; D003432:Cross-Linking Reagents; D000091342:Endoplasmic Reticulum Chaperone BiP; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D007136:Immunoglobulins; D008565:Membrane Proteins; D018832:Molecular Chaperones; C018551:glucose-regulated proteins