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O-GlcNAc modification is an endogenous inhibitor of the proteasome

Fengxue Zhang1, Kaihong Su, Xiaoyong Yang

  • 1Department of Cell Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.

Cell
|December 17, 2003
PubMed

Insights

The O-GlcNAc transferase (OGT) enzyme reversibly modifies the 26S proteasome, inhibiting its function. This O-GlcNAc modification links cellular metabolism to proteasome activity, impacting protein degradation and cellular regulation.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Background:

  • The ubiquitin proteasome system (UPS) is a primary pathway for cellular protein degradation.
  • Proteasome activity is crucial for regulating various cellular processes, including gene expression and protein homeostasis.

Purpose of the Study:

  • To investigate a novel mechanism for global proteasome regulation.
  • To explore the role of O-GlcNAc transferase (OGT) in modulating proteasome function.

Main Methods:

  • In vitro and in vivo assays were used to examine the modification of the 26S proteasome by OGT.
  • Proteolytic activity assays were performed to assess the impact of O-GlcNAc modification on proteasome function.
  • Specific substrates, including transcription factor Sp1 and a hydrophobic peptide, were monitored.

Main Results:

  • The enzyme O-GlcNAc transferase (OGT) was found to inhibit the 26S proteasome through reversible modification.
  • O-GlcNAc modification of the Rpt2 ATPase subunit in the 19S cap was observed both in vitro and in vivo.
  • Increased O-GlcNAc modification correlated with decreased proteasome proteolytic activity, affecting Sp1 and peptide degradation.

Conclusions:

  • O-GlcNAc modification represents a novel mechanism for global control of proteasome function.
  • This modification pathway may link cellular metabolic status to proteasome activity.
  • The O-GlcNAc modification of proteasomes could enable organisms to adapt to metabolic demands by regulating protein and amino acid availability.

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