A molecular census of 26S proteasomes in intact neurons
A molecular census of 26S proteasomes in intact neurons
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DOI：
10.1126/science.1261197
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发表时间：
2015-01-23
期刊：
影响因子：
56.9
通讯作者：
Baumeister, Wolfgang
中科院分区：
文献类型：
--
作者：
Asano, Shoh;Fukuda, Yoshiyuki;Baumeister, Wolfgang
26S 蛋白酶体是真核蛋白质质量控制和众多细胞过程调节的关键角色。在这里，我们描述了完整海马神经元中这种高度动态分子机器的定量原位结构研究。我们使用带有 Volta 相位板的电子冷冻断层扫描技术，实现 26S 蛋白酶体的高保真度和纳米精度定位。我们对单帽和双帽蛋白酶体进行了分子普查，并评估了各个复合物的构象状态。在实验条件下，即在没有蛋白毒性应激的情况下，只有 20% 的 26S 蛋白酶体参与底物加工。其余部分处于基底接受基态。这些发现表明，在没有压力的情况下，蛋白酶体系统的能力没有得到充分利用。
The 26S proteasome is a key player in eukaryotic protein quality control and in the regulation of numerous cellular processes. Here, we describe quantitative in situ structural studies of this highly dynamic molecular machine in intact hippocampal neurons. We used electron cryotomography with the Volta phase plate, which allowed high fidelity and nanometer precision localization of 26S proteasomes. We undertook a molecular census of single-and double-capped proteasomes and assessed the conformational states of individual complexes. Under the conditions of the experiment-that is, in the absence of proteotoxic stress-only 20% of the 26S proteasomes were engaged in substrate processing. The remainder was in the substrate-accepting ground state. These findings suggest that in the absence of stress, the capacity of the proteasome system is not fully used.