Tanaka K, Kumatori A, Ii K, Ichihara A
Institute for Enzyme Research, University of Tokushima, Japan.
J Cell Physiol. 1989 Apr;139(1):34-41. doi: 10.1002/jcp.1041390107.
Subcellular localization of the large multicatalytic protease complexes called proteasomes, which have been found in soluble fractions of various cells, was examined by biochemical, immunological, and immunohistological methods. Rat liver nuclei, purified by two different procedures, showed high activities for degrading [3H]methylcasein and various fluorogenic oligopeptides with neutral and weakly alkaline pH optima. On gel filtration, all of these peptidase activities were recovered in a single peak with the unusually large molecular weight of about 600,000. Properties of the proteolytic activity in crude extracts of the nucleus and the cytoplasm were very similar. Immunoelectrophoretic blot analysis showed the presence of appreciable concentrations of proteasomes with similar immunoreactivity in isolated nuclear and cytosolic fractions. Moreover, immunohistochemical staining of human liver showed that proteasomes were predominantly localized in the nuclear matrix but also were present diffusely in the cytoplasm of hepatocytes. These findings indicate the nuclear and cytoplasmic colocalization of proteasomes.
通过生化、免疫和免疫组织化学方法，对在各种细胞的可溶性组分中发现的称为蛋白酶体的大型多催化蛋白酶复合物进行了亚细胞定位研究。通过两种不同程序纯化的大鼠肝细胞核，对降解[3H]甲基酪蛋白和各种具有中性和弱碱性最适pH值的荧光寡肽表现出高活性。在凝胶过滤中，所有这些肽酶活性都在一个单一峰中回收，其分子量异常大，约为600,000。细胞核和细胞质粗提物中蛋白水解活性的性质非常相似。免疫电泳印迹分析表明，在分离的细胞核和细胞质组分中存在相当浓度的具有相似免疫反应性的蛋白酶体。此外，人肝的免疫组织化学染色表明，蛋白酶体主要定位于核基质中，但也分散存在于肝细胞的细胞质中。这些发现表明蛋白酶体在细胞核和细胞质中共定位。
