Molecular characterization of the "26S" proteasome complex from rat liver.
Molecular characterization of the "26S" proteasome complex from rat liver.
复制标题
大鼠肝脏“26S”蛋白酶体复合物的分子表征。
DOI：
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发表时间：
1993
影响因子：
3
通讯作者：
A. Ichihara
中科院分区：
文献类型：
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作者：
T. Yoshimura;K. Kameyama;Toshio Takagi;A. Ikai;F. Tokunaga;T. Koide;N. Tanahashi;T. Tamura;Z. Cejka;W. Baumeister;Keiji Tanaka;A. Ichihara
从大鼠肝脏中纯化的ATP/泛素依赖的“26 S”蛋白酶体复合物的分子特性进行了研究的理化，生化和形态学分析。在超离心时，蛋白酶体复合物几乎作为单一组分沉降，沉降系数为30.3S。动态光散射测量表明，它的扩散系数为1.38 × 10（-7）cm 2/sec，斯托克斯半径为15.5 nm。根据这两个系数，估计蛋白质复合物具有2.02 × 10（6）的高分子量。静态光散射分析表明分子量为1.91 × 10（6），回转半径为16.8 nm。发现蛋白酶体复合物由分子量为2.1-3.1 × 10（4）的20 S蛋白酶体的多个亚基和分子量为3.5-11.0 × 10（4）的15-20种蛋白质种类组成，这些蛋白质种类与20 S蛋白酶体直接相关。电子显微镜发现，26 S蛋白酶体复合物有一个毛毛虫的形状，20 S蛋白酶体的亚基排列上的直接电镜观察，后者的亚基分为两组序列同源性方面的分类表明，26 S复合物是一个对称的组件的两个域，每个包含一个大的终端子集和一半的中央20 S子集的组件。为了澄清溶液中26 S蛋白酶体复合物的分子结构，使用基于该毛虫形复合物的模型从理论上计算其物理化学参数。得到的斯托克斯半径和回转半径为12.2和14.9 nm的值与实验值一致。这些结果表明，26 S蛋白酶体复合物在溶液中是一个“30 S”的柱状毛虫样结构，由一个具有蛋白水解功能的20 S蛋白酶体组分和多个可能具有调节作用的其它组分组成。
The molecular properties of an ATP/ubiquitin-dependent "26S" proteasome complex purified from rat liver were examined by physicochemical, biochemical, and morphological analyses. On ultracentrifugation, the proteasome complex sedimented as almost a single component with a sedimentation coefficient of 30.3S. Dynamic light-scattering measurements indicated that it has a diffusion coefficient of 1.38 x 10(-7) cm2/sec and a Stokes radius of 15.5 nm. From these two coefficients, the protein complex was estimated to have the high molecular weight of 2.02 x 10(6). Static light-scattering analysis indicated a molecular weight of 1.91 x 10(6) and a radius of gyration of 16.8 nm. The proteasome complex was found to be composed of multiple subunits of the 20S proteasome with molecular weights of 2.1-3.1 x 10(4) and 15-20 protein species with molecular weights of 3.5-11.0 x 10(4), which were directly associated with the 20S proteasome. The electron micrographic finding that the 26S proteasome complex had a caterpillar shape, direct electronmicroscopic observations on the subunit arrangement of the 20S proteasome, and classification of the subunits of the latter into two groups with respect to sequence homology suggested that the 26S complex is a symmetrical assembly of two domains, each containing a large terminal subset and half the central 20S subset of components. For clarification of the molecular structure of the 26S proteasome complex in solution, its physicochemical parameters were calculated theoretically using a model based on this caterpillar-shaped complex. The values obtained for the Stokes radius and radius of gyration of 12.2 and 14.9 nm were consistent with the experimental values. These results provide evidence that the 26S proteasome complex is a cylindrical caterpillar-like structure of "30S" in solution, consisting of a 20S proteasome component with proteolytic function and multiple other components, which possibly have regulatory roles.