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Co-immunoprecipitation Assay for Studying Functional Interactions Between Receptors and Enzymes
Published on: September 28, 2018
PA200 modulates immunoproteasome structure and activity
Dušan Živković1,2,3, Amélie Bosc-Rosati1,2, Angelique Sanchez Dafun1,2
1Université de Toulouse, CNRS, IPBS, Toulouse, France.
Nature Communications
|August 11, 2026
Summary
The proteasome activator PA200 preferentially binds and activates the immunoproteasome (i20S) over the standard proteasome (s20S). This interaction uniquely bends the i20S, enhancing its activity and suggesting PA200 regulates i20S function.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- The proteasome activator PA200 interacts with both standard (s20S) and immunoproteasomes (i20S).
- The precise mechanisms by which PA200 activates i20S are not fully understood.
Purpose of the Study:
- To elucidate the structural and functional mechanisms of PA200 activation of the immunoproteasome (i20S).
- To compare PA200's interaction and activation of i20S versus s20S.
Main Methods:
- Cryo-electron microscopy (cryo-EM) to determine complex structures.
- In vitro biochemical assays to assess proteolytic activity.
- Cellular and tissue expression analysis.
Main Results:
- PA200 binding induces allosteric bending of i20S, widening the opposite α-ring for enhanced binding and activation compared to s20S.
- PA200 selectively enhances i20S peptide production and shifts cleavage specificity towards caspase-like activity.
- PA200 preferentially associates with i20S in cells and tissues, suggesting differential regulation of proteasome subtypes.
Conclusions:
- PA200 plays a significant role in regulating the function and dynamics of the immunoproteasome (i20S).
- PA200 may influence the expression of i20S catalytic subunits.
- These findings reveal a specific regulatory mechanism for i20S by PA200.
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