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| Title | Structural Fluctuations of the Human Proteasome α7 Homo-Tetradecamer Double Ring Imply the Proteasomal α-Ring Assembly Mechanism. |
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| Journal, issue, pages | Int J Mol Sci, Vol. 22, Issue 9, Year 2021 |
| Publish date | Apr 26, 2021 |
 Authors | Chihong Song / Tadashi Satoh / Taichiro Sekiguchi / Koichi Kato / Kazuyoshi Murata /  |
| PubMed Abstract | The 20S proteasome, which is composed of layered α and β heptameric rings, is the core complex of the eukaryotic proteasome involved in proteolysis. The α7 subunit is a component of the α ring, ...The 20S proteasome, which is composed of layered α and β heptameric rings, is the core complex of the eukaryotic proteasome involved in proteolysis. The α7 subunit is a component of the α ring, and it self-assembles into a homo-tetradecamer consisting of two layers of α7 heptameric rings. However, the structure of the α7 double ring in solution has not been fully elucidated. We applied cryo-electron microscopy to delineate the structure of the α7 double ring in solution, revealing a structure different from the previously reported crystallographic model. The D7-symmetrical double ring was stacked with a 15° clockwise twist and a separation of 3 Å between the two rings. Two more conformations, dislocated and fully open, were also identified. Our observations suggest that the α7 double-ring structure fluctuates considerably in solution, allowing for the insertion of homologous α subunits, finally converting to the hetero-heptameric α rings in the 20S proteasome. |
 External links | Int J Mol Sci / PubMed:33926037 / PubMed Central |
| Methods | EM (single particle) |
| Resolution | 5.9 - 11.9 Å |
| Structure data | EMDB-30990, PDB-7e55:  EMDB-30991:  EMDB-30992: |
| Source |
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 Keywords | LYASE / Conformational fluctuation / double-ring / proteasome / D7 symmetry / CHAPERONE |
homo sapiens (human)