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Clastosome: A Subtype of Nuclear Body Enriched in 19S and 20S Proteasomes, Ubiquitin, and Protein Substrates of Proteasome

By Miguel Lafarga, Maria Teresa Berciano, Emma Pena, Isabel Mayo, Jose G. Castaño, Dirk Bohmann, João Pedro Rodrigues, João Paulo Tavanez and Maria Carmo-Fonseca

Abstract

Nuclear bodies represent a heterogeneous class of nuclear structures. Herein, we describe that a subset of nuclear bodies is highly enriched in components of the ubiquitin–proteasome pathway of proteolysis. We coined the term clastosome (from the Greek klastos, broken and soma, body) to refer to this type of nuclear body. Clastosomes contain a high concentration of 1) ubiquitin conjugates, 2) the proteolytically active 20S core and the 19S regulatory complexes of the 26S proteasome, and 3) protein substrates of the proteasome. Although detected in a variety of cell types, clastosomes are scarce under normal conditions; however, they become more abundant when proteasomal activity is stimulated. In contrast, clastosomes disappear when cells are treated with proteasome inhibitors. Protein substrates of the proteasome that are found concentrated in clastosomes include the short-lived transcription factors c-Fos and c-Jun, adenovirus E1A proteins, and the PML protein. We propose that clastosomes are sites where proteolysis of a variety of protein substrates is taking place

Topics: Article
Publisher: The American Society for Cell Biology
Year: 2002
DOI identifier: 10.1091/mbc.E02-03-0122
OAI identifier: oai:pubmedcentral.nih.gov:117941
Provided by: PubMed Central
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