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Covalently Linked Protein Regulators

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Regulated Protein Degradation

Regulated Protein Degradation

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Related Experiment Video

Updated: May 26, 2026

Evaluation of Substrate Ubiquitylation by E3 Ubiquitin-ligase in Mammalian Cell Lysates

Evaluation of Substrate Ubiquitylation by E3 Ubiquitin-ligase in Mammalian Cell Lysates

Published on: May 10, 2022

Cosolutes Modulate Polyubiquitin Fibrillation.

Kalpaja Acharya¹, Sri Rama Koti Ainavarapu², Ranabir Das¹

¹National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India.

|May 25, 2026

Summary

Polyubiquitin forms amyloid-like fibrils, influenced by temperature, pH, and ionic strength. These factors lower the energy barrier for aggregation, impacting neurodegenerative disease research.

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Evaluation of Substrate Ubiquitylation by E3 Ubiquitin-ligase in Mammalian Cell Lysates

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In Vitro Ubiquitination and Deubiquitination Assays of Nucleosomal Histones

In Vitro Ubiquitination and Deubiquitination Assays of Nucleosomal Histones

Published on: July 25, 2019

Area of Science:

Biochemistry
Neuroscience
Molecular Biology

Background:

Ubiquitin is a key post-translational modifier forming polyubiquitin chains.
Ubiquitin aggregates are implicated in neurodegenerative diseases like Alzheimer's and Huntington's.
Polyubiquitin chains can form amyloid-like fibrils in vitro, but the mechanism is unclear.

Purpose of the Study:

To investigate the mechanism of polyubiquitin to amyloid-like fibril conversion.
To identify factors modulating polyubiquitin fibrillation.

Main Methods:

Studied polyubiquitin fibrillation under varying temperature, pH, and ionic strength.
Assessed the impact of cosolutes like ionic liquids and crowding agents on aggregation.

Main Results:

Polyubiquitin forms higher-order oligomeric fibrils.
Temperature, pH, and ionic strength modulate fibrillation rates.
Cosolutes enhance aggregation by lowering the energy barrier to a partially unfolded state (M*) and increasing effective protein concentration.

Conclusions:

Environmental factors and cosolutes significantly influence polyubiquitin aggregation into amyloid-like fibrils.
Understanding these mechanisms is crucial for developing therapies and diagnostics for neurodegenerative diseases.