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Updated: Dec 13, 2025

Exploring Caspase Mutations and Post-Translational Modification by Molecular Modeling Approaches
Published on: October 13, 2022
Post-Translational Modifications of Extracellular Proteasome.
Anna S Tsimokha1, Tatiana O Artamonova1,2, Egor E Diakonov1
1Institute of Cytology of the Russian Academy of Sciences, 4 Tikhoretsky Ave., 194064 Saint-Petersburg, Russia.
Extracellular proteasomes, implicated in disease, show distinct post-translational modifications (PTMs) compared to cellular ones. These PTMs, including novel acetylation sites, may influence extracellular proteasome function and release.
Area of Science:
- Cell Biology
- Biochemistry
- Proteomics
Background:
- The ubiquitin-proteasome system (UPS) is crucial for protein degradation in eukaryotic cells.
- Dysfunctional UPS is linked to cancer and neurological diseases.
- Extracellular 20S proteasomes are elevated in disease states and may have prognostic significance.
Purpose of the Study:
- To investigate the post-translational modifications (PTMs) of extracellular proteasomes in comparison to their cellular counterparts.
- To explore potential mechanisms of extracellular proteasome transport and function.
Main Methods:
- Affinity purification of cellular and extracellular proteasomes.
- SDS-PAGE separation, trypsinization, and MALDI FT-ICR mass spectrometry (MS) analysis.
- Identification and comparison of PTMs between extracellular and cellular proteasomes.
Main Results:
- Identified 64 PTM sites in extracellular proteasomes and 55 in cellular proteasomes.
- Discovered novel acetylation sites specific to extracellular proteasomes (e.g., β2 K238, β3 K192).
- Observed distinct PTMs (acetylation, ubiquitination, succinylation) and crosstalk in both proteasome populations.
Conclusions:
- Extracellular proteasomes exhibit unique PTM profiles compared to intracellular proteasomes.
- These PTMs may play a role in the function and extracellular release of proteasomes.
- Further research is needed to elucidate the functional significance of extracellular proteasome-specific PTMs.
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