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hRpn13/ADRM1/GP110 is a novel proteasome subunit that binds the deubiquitinating enzyme, UCH37
Author(s) -
Qiu XiaoBo,
Ouyang SongYing,
Li ChaoJun,
Miao Shiying,
Wang Linfang,
Goldberg Alfred L
Publication year - 2006
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601450
Subject(s) - deubiquitinating enzyme , proteasome , biology , proteolysis , protein subunit , ubiquitin , biochemistry , microbiology and biotechnology , hek 293 cells , plasma protein binding , transfection , enzyme , receptor , gene
The 26S proteasome catalyzes the degradation of most proteins in mammalian cells. To better define its composition and associated regulatory proteins, we developed affinity methods to rapidly purify 26S proteasomes from mammalian cells. By this approach, we discovered a novel 46‐kDa (407 residues) subunit of its 19S regulatory complex (previously termed ADRM1 or GP110). As its N‐terminal half can be incorporated into the 26S proteasome and is homologous to Rpn13, a 156‐residue subunit of the 19S complex in budding yeast, we renamed it human Rpn13 (hRpn13). The C‐terminal half of hRpn13 binds directly to the proteasome‐associated deubiquitinating enzyme, UCH37, and enhances its isopeptidase activity. Knockdown of hRpn13 in 293T cells increases the cellular levels of ubiquitin conjugates and decreases the degradation of short‐lived proteins. Surprisingly, an overproduction of hRpn13 also reduced their degradation. Furthermore, transfection of the C‐terminal half of hRpn13 slows proteolysis and induces cell death, probably by acting as a dominant‐negative form. Thus in human 26S proteasomes, hRpn13 appears to be important for the binding of UCH37 to the 19S complex and for efficient proteolysis.