Dahlmann B, Ruppert T, Kloetzel P M, Kuehn L
Institut für Biochemie/Charité, Humboldt-Universität Berlin, Monbijoustr. 2, 10117, Berlin, Germany.
Biochimie. 2001 Mar-Apr;83(3-4):295-9. doi: 10.1016/s0300-9084(01)01240-8.
20S proteasomes from tissues and cells are a mixture of several subtypes. From rat skeletal muscle we have tentatively separated six different subtypes of 20S proteasomes purified from rat skeletal muscle by high-resolution anion exchange chromatography. Immunoblot analysis using antibodies to the beta-subunits LMP2, LMP7 and their constitutive counterparts delta and MB1 revealed that two of the three major subtypes (subtypes I and II) are constitutive proteasomes, whereas two of the three minor subtypes belong to the subpopulation of immuno-proteasomes. Subtype III and IV are intermediate-type proteasomes. Enzymological characterisation of the six subtypes revealed clearly different V(max) values for hydrolysis of fluorogenic peptide substrates as well as significantly different activities measured with a 25-mer polypeptide of the murine cytomegalovirus IE pp89 protein as substrate. Our data show that the properties of 20S proteasomes isolated from a given tissue or cells are always the average of the properties of the whole set of proteasome subtypes.
来自组织和细胞的20S蛋白酶体是几种亚型的混合物。我们通过高分辨率阴离子交换色谱法，从大鼠骨骼肌中初步分离出六种不同亚型的20S蛋白酶体。使用针对β亚基LMP2、LMP7及其组成对应物δ和MB1的抗体进行免疫印迹分析表明，三种主要亚型中的两种（亚型I和II）是组成型蛋白酶体，而三种次要亚型中的两种属于免疫蛋白酶体亚群。亚型III和IV是中间型蛋白酶体。对这六种亚型的酶学表征显示，对于荧光肽底物的水解，其V(max)值明显不同，并且以鼠巨细胞病毒IE pp89蛋白的25肽为底物测得的活性也存在显著差异。我们的数据表明，从给定组织或细胞中分离出的20S蛋白酶体的特性始终是整个蛋白酶体亚型集合特性的平均值。
