Association of immunoproteasomes with the endoplasmic reticulum

Brooks, Paul , Murray, Rachael, Mason, Grant, Hendil, Klavs, & Rivett, A.Jennifer (2000) Association of immunoproteasomes with the endoplasmic reticulum. Biochemical Journal, 352, pp. 611-615.

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Proteasomes are complex multisubunit proteases which play a critical role in intracellular proteolysis. Immunoproteasomes, which contain three c-interferon-inducible subunits, are a subset of proteasomes which have a specialized function in antigen processing for presentation by the MHC class I pathway. Two of the c-interferon inducible subunits, LMP2 and LMP7, are encoded within the MHC class II region adjacent to the two TAP (transporter associated with antigen presentation) genes. We have investigated the localization of immunoproteasomes using monoclonal antibodies to LMP2 and LMP7.

Immunoproteasomes were strongly enriched around the endoplasmic reticulum as judged by double-immuno¯uorescence experiments with anticalreticulin antibodies, but were also present in the nucleus and throughout the cytosol. In contrast, proteasome subunit C2, which is present in all proteasomes, was found to be evenly distributed throughout the cytoplasm and in the nucleus, as was the delta subunit, which is replaced by LMP2 in immunoproteasomes. c-Interferon increased the level of immunoproteasomes, but had no effect on their distribution. Our results provide the ®rst direct evidence that immunoproteasomes are strongly enriched at the endoplasmic reticulum, where they may be located close to the TAP transporter to provide efficient transport of peptides into the lumen of the endoplasmic recticulum for association with MHC class I molecules.

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ID Code: 50470
Item Type: Journal Article
Refereed: Yes
Keywords: antigen processing , c-interferon, LMP2, LMP7, MHC class I
DOI: 10.1042/0264-6021:3520611
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
Deposited On: 21 May 2012 23:41
Last Modified: 21 May 2012 23:41

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