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The endoplasmic reticulum stress protein GRP94, in addition to BiP, associates with unassembled immunoglobulin chains

J Melnick1, S Aviel, Y Argon

  • 1Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710.

The Journal of Biological Chemistry
|October 25, 1992
PubMed

Insights

The endoplasmic reticulum stress protein GRP94 acts as a molecular chaperone, similar to BiP/GRP78. Both proteins work together to fold and assemble immunoglobulin chains.

Area of Science:

  • Molecular biology
  • Cellular stress response

Background:

  • The endoplasmic reticulum (ER) is crucial for protein folding and modification.
  • Molecular chaperones, such as BiP/GRP78, assist in protein folding within the ER.
  • The role of other ER stress proteins, like GRP94, in protein folding is less understood.

Purpose of the Study:

  • To investigate the association of GRP94 with immunoglobulin chains.
  • To determine if GRP94 functions as a molecular chaperone.
  • To explore the collaborative roles of BiP and GRP94 in immunoglobulin biogenesis.

Main Methods:

  • Chemical cross-linking to identify protein interactions.
  • Analysis of protein complexes involving immunoglobulin chains, BiP, and GRP94.

Main Results:

  • GRP94 associates with newly synthesized immunoglobulin light and heavy chains.
  • Ternary complexes of immunoglobulin chains, BiP, and GRP94 were identified.
  • Both BiP and GRP94 showed reduced association with fully assembled immunoglobulin compared to unassembled subunits.

Conclusions:

  • GRP94 functions as a molecular chaperone in the endoplasmic reticulum.
  • BiP and GRP94 likely collaborate in the folding and assembly of immunoglobulins.
  • These findings elucidate the coordinated roles of ER stress proteins in protein quality control.

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