Lee D H, Kim S S, Kim K I, Ahn J Y, Shim K S, Nishigai M, Ikai A, Tamura T, Tanaka K, Ichihara A
Department of Molecular Biology, College of Natural Sciences, Seoul National University, Korea.
Biochem Mol Biol Int. 1993 May;30(1):121-30.
The 26S protease complex was purified from chick skeletal muscle and shown to consist of unusually heterogeneous 21-140 kDa polypeptides, including the 21-32 kDa subunits of the 20S proteasome. Electron microscopic analysis revealed that the 26S complex may have a symmetric morphology with two large rectangular terminal domains attached to a thinner central 20S proteasome domain. The 26S complex was capable of degrading the peptide substrates of the 20S proteasome, including Suc-LLVY-AMC, N-Cbz-LLE-NA and N-Cbz-ARR-MNA. The two enzyme complexes showed similar sensitivities to various site-specific protease inhibitors, although their sensitivities to SDS were differed from each other. Immunoprecipitation with anti-26S complex antibody reduced peptide hydrolysis by the 20S proteasome. Similarly, anti-20S proteasome antibody inhibited peptide hydrolysis by the 26S complex. These results demonstrate that the 26S protease complex contains the 20S proteasome as a functional and structural component.
26S蛋白酶复合体从鸡骨骼肌中纯化得到，结果显示它由分子量异常不均一的21 - 140 kDa多肽组成，其中包括20S蛋白酶体的21 - 32 kDa亚基。电子显微镜分析表明，26S复合体可能具有对称形态，两个大的矩形末端结构域连接在较细的中央20S蛋白酶体结构域上。26S复合体能够降解20S蛋白酶体的肽底物，包括琥珀酰-亮-亮-缬-酪-7-氨基-4-甲基香豆素、N-苄氧羰基-亮-亮-谷氨酰胺和N-苄氧羰基-精-精-蛋-4-甲基-7-氨基香豆素。这两种酶复合体对各种位点特异性蛋白酶抑制剂表现出相似的敏感性，尽管它们对十二烷基硫酸钠的敏感性彼此不同。用抗26S复合体抗体进行免疫沉淀可减少20S蛋白酶体的肽水解。同样，抗20S蛋白酶体抗体也抑制26S复合体的肽水解。这些结果表明，26S蛋白酶复合体包含20S蛋白酶体作为其功能和结构组分。
