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Co‐ and post‐translational modifications of the 26S proteasome in yeast
Author(s) -
Kikuchi Julia,
Iwafune Yuko,
Akiyama Tomoko,
Okayama Akiko,
Nakamura Hiroki,
Arakawa Noriaki,
Kimura Yayoi,
Hirano Hisashi
Publication year - 2010
Publication title -
proteomics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.26
H-Index - 167
eISSN - 1615-9861
pISSN - 1615-9853
DOI - 10.1002/pmic.200900283
Subject(s) - proteasome , phosphorylation , biochemistry , saccharomyces cerevisiae , dephosphorylation , acetylation , protein subunit , yeast , phosphatase , biology , chemistry , gene
The yeast ( Saccharomyces cerevisiae ) 26S proteasome consists of the 19S regulatory particle (19S RP) and 20S proteasome subunits. We detected comprehensively co‐ and post‐translational modifications of these subunits using proteomic techniques. First, using MS/MS, we investigated the N ‐terminal modifications of three 19S RP subunits, Rpt1, Rpn13, and Rpn15, which had been unclear, and found that the N ‐terminus of Rpt1 is not modified, whereas that of Rpn13 and Rpn15 is acetylated. Second, we identified a total of 33 Ser/Thr phosphorylation sites in 15 subunits of the proteasome. The data obtained by us and other groups reveal that the 26S proteasome contains at least 88 phospho‐amino acids including 63 pSer, 23 pThr, and 2 pTyr residues. Dephosphorylation treatment of the 19S RP with λ phosphatase resulted in a 30% decrease in ATPase activity, demonstrating that phosphorylation is involved in the regulation of ATPase activity in the proteasome. Third, we tried to detect glycosylated subunits of the 26S proteasome. However, we identified neither N ‐ and O ‐linked oligosaccharides nor O ‐linked β‐ N ‐acetylglucosamine in the 19S RP and 20S proteasome subunits. To date, a total of 110 co‐ and post‐translational modifications, including N α ‐acetylation, N α ‐myristoylation, and phosphorylation, in the yeast 26S proteasome have been identified.