Organization and synergistic binding of copine I and annexin A1 on supported lipid bilayers observed by atomic force microscopy
Organization and synergistic binding of copine I and annexin A1 on supported lipid bilayers observed by atomic force microscopy
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DOI：
10.1016/j.bbamem.2009.06.009
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发表时间：
2009-09-01
影响因子：
3.4
通讯作者：
Edwardson, J. Michael
中科院分区：
文献类型：
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作者：
Creutz, Carl E.;Edwardson, J. Michael
受体活化后，跨细胞质膜的信号转导通常涉及相互作用的蛋白质分子在膜的细胞质表面上的组装。然而，这种复合物形成的结构组织和动力学尚未得到很好的定义。在这项研究中，原子力显微镜被用来监测在体外形成的组件由两类钙依赖性，膜结合蛋白，参与膜上的信号复合物的形成-膜联蛋白和copines。当施加到支持的脂质双层组成的25%脑磷脂酰丝氨酸和75%二油酰磷脂酰胆碱在1 mM的Ca（2+）的存在下，人膜联蛋白A1和人copine I仅结合到专门的域，似乎是0.5至1.0 nm低于其余的双层。这些结构域可能富含磷脂酰丝氨酸，并且具有允许探针穿透的更无序的结构。限制蛋白质与这些结构域的结合在浓缩与Copine或膜联蛋白结合的其他信号蛋白的过程中可能是重要的。膜联蛋白的结合促进了结构域的生长，并为Copine创造了额外的结合空间。这可能反映了膜联蛋白改变膜结构的一般能力，以这种方式包含C2结构域的蛋白质如copine可以结合。Copine I形成了一个网状晶格，由约45 nm长的线性元件组成的专门领域。这种晶格可能为Copine靶蛋白在信号复合物中的组装和相互作用提供支架。(c)2009爱思唯尔有限公司版权所有。
The transduction of signals across the plasma membrane of cells after receptor activation frequently involves the assembly of interacting protein molecules on the cytoplasmic face of the membrane. However, the structural organization and dynamics of the formation of such complexes has not been well defined. In this study atomic force microscopy was used to monitor the assemblies formed in vitro by two classes of calcium-dependent, membrane-binding proteins that participate in the formation of signaling complexes on membranes - the annexins and the copines. When applied to supported lipid bilayers composed of 25% brain phosphatidylserine and 75% dioleyl phosphatidylcholine in the presence of 1 mM Ca(2+) both human annexin A1 and human copine I bound only to specialized domains that appeared to be 0.5 to 1.0 nm lower than the rest of the bilayer. These domains may be enriched in phosphatidylserine and have a more disordered structure allowing probe penetration. Confinement of the binding of the proteins to these domains may be important in the process of concentrating other signaling proteins bound to the copine or annexin. The binding of the annexin promoted the growth of the domains and created additional binding space for the copine. This may reflect a general ability of annexins to alter membrane structure in such a way that C2 domain-containing proteins like copine can bind. Copine I formed a reticular lattice composed of linear elements approximately 45 nm long on the specialized domains. This lattice might provide a scaffold for the assembly and interaction of copine target proteins in signaling complexes. (c) 2009 Elsevier B.V. All rights reserved.