C3D/EBV RECEPTOR LIGAND BINDING SITES

描述（改编自研究者摘要）：续 对补体受体CR2表达结构域的结构研究是 提出了补体受体2型（CR2，CD 21）通常作为受体 补体C3激活片段和免疫调节蛋白CD 23。 B淋巴细胞的表达是正常体液免疫的发展所必需的。 对外来抗原的免疫反应。这是由于CR2的能力， 将C3片段iC 3b和C3 d，g与抗原的结合功能性地连接， B淋巴细胞蛋白CD 19的信号转导能力。此外 Epstein-Bar病毒（EBV）利用CR2作为其感染的主要手段 细胞 研究人员沿着其他研究小组先前研究了 结构-功能关系，控制CR2与 上述配体使用涉及诱变和抗体结合的策略。 他们发现，一个由两个60-70个氨基酸片段组成的结构域， N-末端短共有重复序列（SCR）仅包含两个结合位点 对于C3片段和EBV蛋白gp 350/220，并且含有两个 CD 23的位置。CR2的这个结构域和CD 3的位置的模型 结合位点已经产生，但实际的三维结构是 不知道。 研究人员建议应用核磁共振方法来确定这三个 CR2结构域的三维结构。他们建议进一步描述 使用诱变和抑制剂技术的配体结合位点。他们还 建议确定这个结构域如何与CR2的其他区域相互作用。更 具体而言，他们的三个具体目标是：1）确定结构， 人CR2 SCR 1-2结构域的高分辨率。2）定义配体结合 人CR2 SCR 1-2结构域中C3活化片段iC 3b的位点， C3 d，g除了EBV gp 350/220和CD 23的结合位点之外。3)建立 较长CR2区域的三维溶液相结构， SCR 1-2结构域，并确定该结构域的取向是否 受其羧基末端侧翼SCR的影响。

Description (Adapted from Investigator's Abstract): A continuation of structural investigations on expressed domains from Complement Receptor CR2 is proposed. Complement receptor type 2 (CR2, CD21) normally serves as a receptor for complement C3 activation fragments and the immuno-modulatory protein CD23. Expression by B lymphocytes is required for the development of a normal humoral immune response to foreign antigens. This is due to the ability of CR2 to functionally link the binding of C3 fragments iC3b and C3d,g with antigen to the signal transducing capability of the B lymphocyte protein CD19. In addition the Epstein-Bar virus (EBV) utilizes CR2 as its primary means of infecting cells. The investigators along with other groups have previously studied structure-function relationships that govern the interaction of CR2 with the above ligands using strategies involving mutagenesis, and antibody binding. They have found that a domain composed of two 60-70 amino acid segments called N-terminal short consensus repeats (SCRs) contain the only two binding sites for C3 fragments and the EBV protein gp350/220, and contain one of the two sites for CD23. A model for this domain of CR2 and the location of the CD3 binding sites has been created, but the actual three dimensional structure is not known. The investigators propose to apply an NMR method for determining the three dimensional structure of the CR2 domain. They propose to further characterize ligand binding sites using mutagenesis and inhibitor techniques. They also propose to determine how this domain interacts with other regions of CR2. More specifically, their three specific aims are: 1)to determine the structure at high resolution of the human CR2 SCR 1-2 domain. 2)to define the ligand binding sites in the human CR2 SCR 1-2 domain for C3 activation fragments iC3b and C3d,g in addition to binding sites for EBV gp350/220 and CD23. 3) to establish the 3-dimensional solution phase structure of a longer CR2 region containing the SCR 1-2 domain and determine whether the orientation of this domain is influenced by its carboxy-terminal flanking SCRs.