Lupas A, Koster A J, Baumeister W
Max-Planck-Institut für Biochemie, Martinsried, Deutschland.
Enzyme Protein. 1993;47(4-6):252-73. doi: 10.1159/000468684.
The 26S proteasome is the central protease of the ubiquitin-dependent pathway of protein degradation and has a highly conserved structure from slime molds to humans. The elongated molecule which has a molecular mass of approximately 2,000 kD is formed by a barrel-shaped 20S core complex and two polar 19S complexes. The 20S complex has C2 symmetry and is built by four seven-membered rings of which the outer rings are rotated by 26 degrees relative to the inner rings while the inner rings are in register. The 19S cap complex is asymmetric and therefore considerably less well understood on a structural level. From a comparison of the activity and regulation of the 26S and 20S particles, it can be deduced that the 20S particle contains the protease activity while the 19S complex is supposed to contain isopeptidase, oxidoreductase, ATPase and protein-unfolding activities. In this article we describe the structure of various proteasome complexes as determined by electron microscopy and discuss structural implications of their subunit sequences.
26S蛋白酶体是蛋白质降解的泛素依赖性途径的核心蛋白酶，其结构从黏菌到人类都高度保守。这种分子量约为2000kD的细长分子由一个桶状的20S核心复合物和两个极性的19S复合物组成。20S复合物具有C2对称性，由四个七元环构成，其中外环相对于内环旋转26度，而内环是对齐的。19S帽复合物是不对称的，因此在结构层面上的了解要少得多。通过比较26S和20S颗粒的活性和调控，可以推断20S颗粒含有蛋白酶活性，而19S复合物则被认为含有异肽酶、氧化还原酶、ATP酶和蛋白质解折叠活性。在本文中，我们描述了通过电子显微镜确定的各种蛋白酶体复合物的结构，并讨论了其亚基序列的结构意义。
