Ubiquitin-dependent protein degradation is not only involved in the recycling of amino acids from damaged or misfolded proteins but also represents an essential and deftly controlled mechanism for modulating the levels of key regulatory proteins. Chains of ubiquitin conjugated to a substrate protein specifically target it for degradation by the 26S proteasome, a huge multi-subunit protein complex found in all eukaryotic cells. Recent reports have clarified some of the molecular mechanisms involved in the transfer of ubiquitinated substrates from the ubiquitination machinery to the proteasome. This novel substrate transportation step in the ubiquitin-proteasome pathway seems to occur either directly or indirectly via certain substrate-recruiting proteins and appears to involve chaperones.

中文翻译：

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将底物转移至26S蛋白酶体。

泛素依赖性蛋白质降解不仅涉及从受损或错误折叠的蛋白质中回收氨基酸，还代表了调节关键调节蛋白水平的重要且灵敏的控制机制。与底物蛋白结合的泛素链特异性地将其靶向26S蛋白酶体降解，而26S蛋白酶体是在所有真核细胞中都发现的巨大的多亚基蛋白复合物。最近的报道已经阐明了泛素化底物从泛素化机制向蛋白酶体转移的一些分子机制。遍在蛋白-蛋白酶体途径中的这种新的底物转运步骤似乎是通过某些底物刺激蛋白直接或间接发生的，并且似乎涉及伴侣分子。