STRUCTURE AND EXPRESSION OF COMPLEMENT GENES

在过去的10年里，重组DNA克隆和测序研究 阐明了补体蛋白家族的一级结构 由C3、C4和C5组成。 本申请提出 利用这些序列信息以及蛋白质表达， 诱变方法，和肽抑制策略，以探测 最重要的功能特性的结构基础， 这3种蛋白质：通过蛋白水解裂解激活。 尽管 在它们的激活位点C3、C4和C5处非常相似的序列， 被不同的蛋白酶特异性地切割。 拟议的研究是 旨在确定C3和C5的结构特征， 对于被其特异性蛋白酶识别是重要的。 要使用的突变策略集中在以长度标记的区域 多态性（indels）在这个蛋白质家族。 选择这一策略 因为插入缺失通常与蛋白质表面上的环相关， 一般来说，表面环路或转弯可能涉及到一个 各种分子间识别事件。 Indels可以发挥作用， 在成员之间不同职能的演变中发挥重要作用， 蛋白质家族 在为鉴定蛋白酶提供理论基础时， 在C3和C5上的识别位点，这种策略表明了一种全面的 这些蛋白质的结构结合了我们所知道的 它们的一级结构，它们的基因结构（插入缺失通常是 在内含子-外显子连接处发现），以及 天然蛋白质 因此，拟议的研究也提供了一个测试， 风景 这项研究计划的长期目标是确定， 这个家庭的成员，共同形成其结构特征， 独特的生物化学和功能特性。 这些信息将 提供详细的分子见解如何这些蛋白质的功能， 一般来说，这些蛋白质直接相互作用， 与大多数其他补体蛋白质，是补体的重点， 激活、调节和补体受体介导的细胞 交互. 这种对补体功能的了解可能有助于 设计干预策略，例如使用合成肽 在补体激活是不希望的情况下，例如 如慢性炎症和超急性排斥反应 异种组织移植

Over the past 10 years, recombinant DNA cloning and sequencing studies have elucidated the primary structures of the complement protein family that is composed of components C3, C4, and C5. This application proposes to use this sequence information, together with protein expression and mutagenesis methods, and a peptide inhibition strategy to probe the structural basis for the most important functional property shared by these 3 proteins: activation by proteolytic cleavage. Despite having very similar sequences at their activation sites, C3, C4, and C5 are specifically cleaved by distinct proteases. The proposed studies are aimed at identifying the structural features of C3 and C5 that are important for recognition by their specific proteases. The mutational strategy to be used focuses on regions marked by length polymorphisms (indels) in this protein family. This strategy was chosen because indels are usually associated with loops on the protein surface, and surface loops or turns are, in general, likely to be involved in a variety of intermolecular recognition events. Indels may play an important role in the evolution of distinct functions among members of a protein family. In providing a rationale for identifying the protease recognition sites on C3 and C5, this strategy suggests a comprehensive view of the structures of these proteins which combines what we know of their primary structures, the structures of their genes (indels are often found at intron-exon junctions), and the functional properties of the native proteins. Hence, the proposed studies also provide a test of this view. The long-term goal of this research program is to identify, for each member of this family, the structural features that together form their unique biochemical and functional properties. This information will provide detailed molecular insights into how these proteins function, and into complement function in general, as these proteins interact directly with most other complement proteins, and are the focus of complement activation, regulation, and complement receptor-mediated cellular interactions. This insight into complement function may aid in the design of intervention strategies such as the use of synthetic peptide inhibitors in situations where complement activation is undesirable, such as in chronic inflammation and in the hyperacute rejection associated with xenogeneic tissue transplantation.