Different ratios in 20 S proteasomes and regulatory subunit complexes in two isoforms of the 26 S proteasome purified from rabbit skeletal muscle

FEBS Letters

Muto, Kazuko²  Akaishi, Takahiro²  Sawada, Hitoshi²  Goldberg, Alfred L.¹  Sawada, Michiko Takagi¹  Fujimuro, Masahiro²  Yokosawa, Hideyoshi² 

[1] Department of Cellular and Molecular Physiology, Harvard Medical School, Boston, MA 02115, USA;Department of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo 060, Japan

关键词: ATP-dependent;    Ubiquitin;    Protease;    Proteasome;    Muscle (rabbit);    AMC;    7-amino-4-methylcoumarin;    DMA;    dimethyladipimidate;    DTT;    dithiothreitol;    DTBP;    dimethyl 3;    3'-dithiobispropionimidate;    MCA;    4-methylcoumaryl-7-amide;    PAGE;    polyacrylamide gel electrophoresis;    SDS;    sodium dodecyl sulfate;    Suc;    succinyl;    2D;    two-dimensional;    Ub;    ubiquitin;   

DOI  :  10.1016/0014-5793(93)80731-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A ubiquitin/ATP-dependent proteinase complex (26 S proteasome) was highly purified from rabbit skeletal muscle. The purified 26 S proteasome easily dissociated into a 20 S proteasome and a regulatory subunit complex on non-denaturing PAGE. By using cleavable and non-cleavable cross-linkers, it was revealed that the 26 S proteasome exists in two isoforms: one (D complex) consists of the 20 S proteasome and the regulatory subunit complex in the ratio of one to two, while the other (C complex) exists in an equal molar ratio. Molecular masses of the former and the latter isoforms were estimated to be 1,700 kDa and 1,400 kDa, respectively, by gel filtration, and 2,400 kDa and 1,400 kDa, respectively, by Ferguson plot analysis. Furthermore, both isoforms efficiently hydrolyzed Suc-Leu-Leu-Val-Tyr-MCA and ubiquitin-conjugated [¹²⁵I]lysozyme. These results suggest that the D and C complexes are active proteinase complexes, most probably corresponding to the dumbbell-like and mushroom-like (or space capsule-like) molecules, respectively.

【 授权许可】

Unknown