Tanaka K
The Tokyo Metropolitan Institute of Medical Science, and CREST, Japan Science and Technology Corporation.
J Biochem. 1998 Feb;123(2):195-204. doi: 10.1093/oxfordjournals.jbchem.a021922.
The proteasome is a multisubunit protease complex with an apparent sedimentation coefficient of 20S. Two types of regulatory complexes, named PA700 and PA28, bind to both ends of the cylindrical 20S proteasome to form the dumbbell-like and football-like proteasomes, respectively. The former complex, named the 26S proteasome, is a eukaryotic ATP-dependent protease and appears to be well organized as a large complex of 2 MDa, consisting of approximately 40 polypeptides, to facilitate rapid proteolysis. It is assumed to be a protein "death machine", destroying a variety of cellular proteins that have acquired a specific degradation signal(s) such as a multiubiquitin chain. Recently data on in vivo substrates for the ubiquitin-proteasome pathway have been accumulating rapidly, implying its involvement in many biologically important processes, such as cell-cycle regulation, signal transduction, protein quality control, and the immune response. The newly-identified PA28 family proteins are inducible by interferons, and may cooperate with the 26S proteasome or play additional roles. Since the proteasome is capable of catalyzing breakdown of proteins not only irreversibly, but also rapidly and timely, it is thought to be a new regulatory system for biological reactions in eukaryotes.
蛋白酶体是一种多亚基蛋白酶复合体，其表观沉降系数为20S。两种类型的调节复合体，分别称为PA700和PA28，结合到圆柱形20S蛋白酶体的两端，分别形成哑铃状和足球状蛋白酶体。前一种复合体，即26S蛋白酶体，是一种真核生物ATP依赖性蛋白酶，似乎是一个组织良好的2MDa大复合体，由大约40种多肽组成，以促进快速蛋白水解。它被认为是一种蛋白质“死亡机器”，可破坏各种已获得特定降解信号（如多聚泛素链）的细胞蛋白质。最近，关于泛素-蛋白酶体途径的体内底物的数据迅速积累，这意味着它参与了许多生物学上重要的过程，如细胞周期调控、信号转导、蛋白质质量控制和免疫反应。新鉴定的PA28家族蛋白可被干扰素诱导，可能与26S蛋白酶体协同作用或发挥其他作用。由于蛋白酶体不仅能够不可逆地、而且能够快速及时地催化蛋白质分解，因此它被认为是真核生物中生物反应的一种新的调节系统。
