Function of the p97-Ufd1-Npl4 complex in retrotranslocation from the ER to the cytosol: dual recognition of nonubiquitinated polypeptide segments and polyubiquitin chains.
Function of the p97-Ufd1-Npl4 complex in retrotranslocation from the ER to the cytosol: dual recognition of nonubiquitinated polypeptide segments and polyubiquitin chains.
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p97-UFD1-NPL4复合物在从ER到胞质溶液的转向转换中的功能：非泛素化多肽片段和多泛素链的双重识别。
DOI：
10.1083/jcb.200302169
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发表时间：
2003-07-07
影响因子：
7.8
通讯作者：
Rapoport, Tom A
中科院分区：
文献类型：
--
作者：
Ye, Yihong;Meyer, Hemmo H;Rapoport, Tom A
与多种细胞活动相关的 ATP 酶家族的成员（在哺乳动物中称为 p97，在酵母中称为 Cdc48）与辅因子 Ufd1-Npl4 结合，将多泛素化多肽从内质网 (ER) 膜转移到胞质溶胶中，随后被蛋白酶体降解。在这里，我们研究了 p97-Ufd1-Npl4 复合物在此逆转位途径中发挥作用的机制。当 p97 的第一个 ATP 酶结构域（D1 结构域）处于核苷酸结合状态时，就会发生底物结合，这种相互作用也需要 p97 通过其 NH2 末端结构域与膜结合。 p97 的两个 ATP 酶结构域（D1 和 D2）似乎在 ATP 水解中交替，这对于多肽从 ER 膜移动到细胞质中至关重要。当未修饰的多肽底物从 ER 膜中出现时，ATP 酶本身可以与它们相互作用。由赖氨酸 48 连接的多聚泛素链可被 p97 和 Ufd1 NH2 末端进化上保守的泛素结合位点以协同方式识别。我们提出了一种双重识别模型，其中 ATP 酶复合物结合底物的未修饰片段和附着的多聚泛素链；多聚泛素结合可激活 ATP 酶 p97，将多肽底物拉出膜。
Amember of the family of ATPases associated with diverse cellular activities, called p97 in mammals and Cdc48 in yeast, associates with the cofactor Ufd1–Npl4 to move polyubiquitinated polypeptides from the endoplasmic reticulum (ER) membrane into the cytosol for their subsequent degradation by the proteasome. Here, we have studied the mechanism by which the p97–Ufd1–Npl4 complex functions in this retrotranslocation pathway. Substrate binding occurs when the first ATPase domain of p97 (D1 domain) is in its nucleotide-bound state, an interaction that also requires an association of p97 with the membrane through its NH2-terminal domain. The two ATPase domains (D1 and D2) of p97 appear to alternate in ATP hydrolysis, which is essential for the movement of polypeptides from the ER membrane into the cytosol. The ATPase itself can interact with nonmodified polypeptide substrates as they emerge from the ER membrane. Polyubiquitin chains linked by lysine 48 are recognized in a synergistic manner by both p97 and an evolutionarily conserved ubiquitin-binding site at the NH2 terminus of Ufd1. We propose a dual recognition model in which the ATPase complex binds both a nonmodified segment of the substrate and the attached polyubiquitin chain; polyubiquitin binding may activate the ATPase p97 to pull the polypeptide substrate out of the membrane.