The physiological role of the free 20S proteasome in protein degradation: A critical review

• Published in: Biochimica et biophysica acta. General subjects Vol. 1862; no. 12; pp. 2948 - 2954
• Main Authors: Demasi, Marilene, da Cunha, Fernanda Marques
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.12.2018
• Subjects: Adenosine Triphosphate - metabolism; Catalysis; Hydrophobic and Hydrophilic Interactions; oxidation; Oxidation-Reduction; Proteasomal complexes; proteasome endopeptidase complex; Proteasome Endopeptidase Complex - physiology; protein degradation; proteins; Proteolysis; Ubiquitin - metabolism; Ubiquitin- and ATP-independent protein degradation; Ubiquitin-proteasome system; Ubiquitin-proteasome system; Ubiquitin- and ATP-independent protein degradation; Proteasomal complexes
• ISSN: 0304-4165; 1872-8006; 1872-8006
• DOI: 10.1016/j.bbagen.2018.09.009

It has been almost three decades since the removal of oxidized proteins by the free 20S catalytic unit of the proteasome (20SPT) was proposed. Since then, experimental evidence suggesting a physiological role of proteolysis mediated by the free 20SPT has being gathered. Experimental data that favors the hypothesis of free 20SPT as playing a role in proteolysis are critically reviewed. Protein degradation by the proteasome may proceed through multiple proteasome complexes with different requirements though the unequivocal role of the free 20SPT in cellular proteolysis towards native or oxidized proteins remains to be demonstrated. The biological significance of proteolysis mediated by the free 20SPT has been elusive since its discovery. The present review critically analyzes the available experimental data supporting the proteolytic role of the free or single capped 20SPT.