MACCHESS PROGRAM FOR MICROCRYSTALLOGRAPHY/MEMBRANE PROTEIN CRYSTALS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 1.与Cdc42作用相关的信号复合体的结构： 我们实验室的一个主要重点是了解GTP结合蛋白如何在细胞信号通路中扮演分子开关的角色。其中一个重点领域是与RAS相关的GTP结合蛋白CDC42，它是从酵母到人类最保守的GTP结合蛋白之一。Cdc42已被证明在细胞生物学中扮演着许多基本的重要角色。CDC42的过度激活会导致细胞恶性转化。这涉及到一条由Cdc42介导的信号通路，该通路调节生长因子受体的信号寿命和运输。特别是，活化的CDC42与g辅酶原(GCOP)亚单位的结合对于这种转运功能是必不可少的，g辅基是包裹在运输囊泡上的多蛋白复合体的一部分。我们一直感兴趣的是确定活化的CDC42如何与g-辅酶原结合，以及g-辅酶原如何与COPI复合体的相关亚基结合来参与运输囊泡的组装。最近，基于我们在MacCHESS收集的数据，我们已经发表了g-辅酶A亚单位氨基末端一半的结构，分辨率为2.1埃(参见下文Hoffman等人)。这使得我们能够提出一个关于COPI运输囊泡如何组装的模型。值得注意的是，COPI复合体的组装似乎类似于指导形成笼蛋白包裹的囊泡和受体内吞的适配器复合体的组装。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 1.Structures of signaling complexes relevant to the actions of Cdc42: A major emphasis of our laboratory has been directed at understanding how GTP-binding proteins act as molecular switches in cell signaling pathways. One area of emphasis has been the Ras-related GTP-binding protein, Cdc42, which is one of the most highly conserved GTP-binding proteins from yeast to humans. Cdc42 has been shown to play a number of fundamentally important roles in cell biology. The hyper-activation of Cdc42 leads to malignant transformation. This involves a Cdc42-mediated signaling pathway that regulates the signaling lifetime and trafficking of growth factor receptors. In particular, the binding of activated Cdc42 to the g coatomer (gCOP) subunit, which is part of a multi-protein complex that coats trafficking vesicles, is essential for this trafficking function. We have been interested in determining how activated Cdc42 binds to the g-coatomer subunit and how g-coatomer engages associated subunits of the COPI complex to participate in the assembly of trafficking vesicles. Recently, we have published the structure for the amino-terminal half of the g-coatomer subunit to 2.1 angstrom resolution, based on data that we collected at MacCHESS (see Hoffman et al., below). This has allowed us to propose a model regarding how COPI trafficking vesicles assemble. Remarkably, it appears that the assembly of the COPI complex is similar to the assembly of the adaptor complexes that direct the formation of clathrin-coated vesicles and receptor endocytosis.