QUT ePrints

Subcellular localization of proteasomes and their regulatory complexes in mammalian cells

Brooks, Paul, Fuertes, Graciela, Murray, Rachael, Bose, Suchira, Knecht, Erwin, Rechsteiner, Martin, Hendil, Klavs, Tanaka, Keiji, Dyson, Julian, & Rivett, A.Jennifer (2000) Subcellular localization of proteasomes and their regulatory complexes in mammalian cells. Biochemical Journal, 346(Part 1), pp. 155-161.

View at publisher

Abstract

Proteasomes can exist in several different molecular forms in mammalian cells. The core 20S proteasome, containing the proteolytic sites, binds regulatory complexes at the ends of its cylindrical structure. Together with two 19S ATPase regulatory complexes it forms the 26S proteasome, which is involved in ubiquitin-dependent proteolysis. The 20S proteasome can also bind 11S regulatory complexes (REG, PA28) which play a role in antigen processing, as do the three variable c-interferoninducible catalytic b-subunits (e.g. LMP7). In the present study, we have investigated the subcellular distribution of the different forms of proteasomes using subunit speci®c antibodies. Both 20S proteasomes and their 19S regulatory complexes are found in nuclear, cytosolic and microsomal preparations isolated from rat liver. LMP7 was enriched approximately two-fold compared with core a-type proteasome subunits in the microsomal preparations. 20S proteasomes were more abundant than 26S proteasomes, both in liver and cultured cell lines. Interestingly, some signi®cant differences were observed in the distribution of different subunits of the 19S regulatory complexes. S12, and to a lesser extent p45, were found to be relatively enriched in nuclear fractions from rat liver, and immuno¯uorescent labelling of cultured cells with anti-p45 antibodies showed stronger labelling in the nucleus than in the cytoplasm. The REG was found to be localized predominantly in the cytoplasm. Three- to six-fold increases in the level of REG were observed following cinterferon treatment of cultured cells but c-interferon had no obvious effect on its subcellular distribution. These results demonstrate that different regulatory complexes and subpopulations of proteasomes have different distributions within mammalian cells and, therefore, that the distribution is more complex than has been reported for yeast proteasomes.

Impact and interest:

203 citations in Scopus
Search Google Scholar™
199 citations in Web of Science®

Citation countsare sourced monthly from Scopus and Web of Science® citation databases.

These databases contain citations from different subsets of available publications and different time periods and thus the citation count from each is usually different. Some works are not in either database and no count is displayed. Scopus includes citations from articles published in 1996 onwards, and Web of Science® generally from 1980 onwards.

Citations counts from the Google Scholar™ indexing service can be viewed at the linked Google Scholar™ search.

ID Code: 50476
Item Type: Journal Article
Keywords: ATPase complex, interferon-c, PA28, 19S complex
ISSN: 0264-6021
Subjects: Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > BIOCHEMISTRY AND CELL BIOLOGY (060100) > Protein Trafficking (060108)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Deposited On: 22 May 2012 11:07
Last Modified: 23 May 2012 10:45

Export: EndNote | Dublin Core | BibTeX

Repository Staff Only: item control page