Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, USA.
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.
Nat Struct Mol Biol. 2024 Jun;31(6):910-924. doi: 10.1038/s41594-023-01184-4. Epub 2023 Dec 7.
The recycling of membrane proteins from endosomes to the cell surface is vital for cell signaling and survival. Retriever, a trimeric complex of vacuolar protein-sorting-associated protein (VPS)35L, VPS26C and VPS29, together with the CCC complex comprising coiled-coil domain-containing (CCDC)22, CCDC93 and copper metabolism domain-containing (COMMD) proteins, plays a crucial role in this process. The precise mechanisms underlying retriever assembly and its interaction with CCC have remained elusive. Here, we present a high-resolution structure of retriever in humans determined using cryogenic electron microscopy. The structure reveals a unique assembly mechanism, distinguishing it from its remotely related paralog retromer. By combining AlphaFold predictions and biochemical, cellular and proteomic analyses, we further elucidate the structural organization of the entire retriever-CCC complex across evolution and uncover how cancer-associated mutations in humans disrupt complex formation and impair membrane protein homeostasis. These findings provide a fundamental framework for understanding the biological and pathological implications associated with retriever-CCC-mediated endosomal recycling.
内体到细胞表面的膜蛋白循环对于细胞信号转导和存活至关重要。Retriever 是一种由三聚物组成的复合物,包括液泡蛋白分选相关蛋白 (VPS)35L、VPS26C 和 VPS29,以及包含卷曲螺旋域包含 (CCDC)22、CCDC93 和铜代谢域包含 (COMMD) 蛋白的 CCC 复合物,在这个过程中起着关键作用。Retriever 组装的精确机制及其与 CCC 的相互作用仍然难以捉摸。在这里,我们使用低温电子显微镜确定了人类中 retriever 的高分辨率结构。该结构揭示了一种独特的组装机制,使其与远相关的同源蛋白 retromer 区分开来。通过结合 AlphaFold 预测和生化、细胞和蛋白质组学分析,我们进一步阐明了整个 retriever-CCC 复合物在进化过程中的结构组织,并揭示了人类中与癌症相关的突变如何破坏复合物形成并损害膜蛋白的动态平衡。这些发现为理解与 retriever-CCC 介导的内体回收相关的生物学和病理学意义提供了一个基本框架。
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