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NF-kappa B/Rel family members are physically associated phosphoproteins

C C Li1, M Korner, D K Ferris

  • 1Biological Carcinogenesis and Development Program, Program Resources, Inc./DynCorp., NCI-Frederick Cancer Research and Development Center 21702-1201.

The Biochemical Journal
|October 15, 1994
PubMed

Insights

NF-kappa B/Rel proteins form complexes with inhibitors like I kappa B alpha in Jurkat T cells. These proteins are phosphoproteins, and their phosphorylation patterns change upon stimulation.

Area of Science:

  • Immunology
  • Molecular Biology
  • Cell Signaling

Background:

  • The NF-kappa B/Rel family plays a crucial role in immune responses and cellular signaling.
  • Inhibitors such as I kappa B alpha regulate NF-kappa B activity.
  • Understanding the post-translational modifications and interactions of these proteins is key to deciphering their function.

Purpose of the Study:

  • To investigate the complex formation and phosphorylation status of NF-kappa B/Rel family proteins and their inhibitors in Jurkat T cells.
  • To characterize the changes in phosphorylation upon stimulation with phorbol 12-myristate 13-acetate and phytohaemagglutinin.

Main Methods:

  • Radioimmunoprecipitation followed by serial immunoblots.
  • In vivo and in vitro phosphorylation experiments.
  • Phosphopeptide mapping.

Main Results:

  • NF-kappa B/Rel proteins (p80-c-Rel, p105-NF-kappa B, p65-NF-kappa B, p50-NF-kappa B) and the inhibitor p36-I kappa B alpha were detected in complexes in unstimulated Jurkat cells.
  • p36-I kappa B alpha and p105 associate with NF-kappa B/Rel members but not each other.
  • NF-kappa B/Rel family members and p36-I kappa B alpha are phosphoproteins, with both unphosphorylated and hyperphosphorylated forms of p36-I kappa B alpha found in complexes.
  • Stimulation led to increased phosphorylation of p105-NF-kappa B and p50-NF-kappa B, with qualitative changes in p105 phosphorylation.

Conclusions:

  • NF-kappa B/Rel proteins and their inhibitors exist in complexes and are subject to phosphorylation.
  • Hyperphosphorylated I kappa B alpha remains capable of complex formation.
  • Stimulation alters the phosphorylation state of key NF-kappa B pathway components, suggesting dynamic regulation.

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