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Replacement of proteasome subunits X and Y by LMP7 and LMP2 induced by interferon‐γ for acquirement of the functional diversity responsible for antigen processing
Author(s) -
Akiyama Kinya,
Kagawa Susumu,
Tamura Tomohiro,
Shimbara Naoki,
Takashina Makoto,
Kristensen Poul,
Hendil Klavs B.,
Tanaka Keiji,
Ichihara Akira
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)80612-8
Subject(s) - proteasome , protein subunit , antigen processing , antigen presentation , antigen , mhc class i , biology , interferon , microbiology and biotechnology , major histocompatibility complex , ubiquitin , chemistry , biochemistry , immunology , cytotoxic t cell , gene , in vitro
Proteasomes catalyze the non‐lysosomal, ATP‐dependent selective breakdown of ubiquitinated proteins and are thought to be responsible for MHC class I‐restricted antigen presentation. Recently, we reported that gamma interferon (IFN‐γ) induced not only marked synthesis of the MHC‐encoded proteasome subunits LMP2 and LMP7, but also almost complete loss of two unidentified proteasome subunits tentatively designated as X and Y in various human cells. Here, we show that subunit X is a new proteasomal subunit highly homologous to LMP7, and that subunit Y is identical to the LMP2‐related proteasomal subunit delta. Thus, IFN‐γ appears to induce subunit replacements of X and Y by LMP7 and LMP2, respectively, producing 'immuno‐proteasomes' with the functional diversity responsible for processing of endogenous antigens.