FIBRONECTIN-IMMUNOGLOBULIN INTERACTION

纤维连接蛋白（Fn）是一种高分子量的细胞表面和血浆 由离散的配体结合结构域组成的糖蛋白（胶原， 纤维蛋白、肝素等），其介导各种生物活性。 Fn有 还发现与cryopulins和免疫复合物（IC）相关。 我们的研究表明，IgG的主要免疫球蛋白（IG）类别， IgM和伊加特异性结合Fn的三个独立区域， 分子。 检查生物化学性质和结构/功能 Fn/IG相互作用的关系，我们计划确定主要的 结构在IG和Fn，参与这种相互作用。 这将 通过两种方式实现：1）通过获得Fn的蛋白水解片段 和保留其结合能力的Ig用于氨基酸测序。 2)通过在竞争性ELISA中抑制Fn与Ig的相互作用 使用遗传克隆的Fn（I型重复）的氨基酸序列 模块）和Fn和Ig的合成肽。 因为Fn是调理素， Fn/IG相互作用的重要性与加速的 从循环和沉积部位清除IC。 从 从病理学角度考虑，Fn与IG的相互作用可能是 参与免疫复合物疾病（ICD）的病因学，如 在许多骨髓增生性和自身免疫性疾病中观察到， 炎症是由于IC在组织中的沉积， Fn。 我们计划比较Fn与 正常免疫球蛋白和冷球蛋白，通过ELISA，并确定是否有最低 IG复合物的聚集体大小可能决定了IC与Fn的结合。 将产生含Fn的细胞外基质（ECM）（无细胞的 细胞裂解后）并用作体外模型以测试IC 结合;该系统应提供IC的体内相关性 在组织中沉积。 测定Fn的Ig结合肽序列， 通过结构研究，将用于抑制IC与 ECM。 有效抑制将证明ECM Fn（组织）的作用 在ICs的隔离中，从而暗示Fn的相互作用， IG参与了ICD的发病机制。 Fn与 IG应提供对ICD病因的深入了解，并阐明 参与正常宿主免疫功能的机制。

Fibronectin (Fn) is a high molecular weight cell surface and plasma glycoprotein composed of discrete ligand binding domains (collagen, fibrin, heparin, etc) that mediate various biological activities. Fn has also been found associated with cryoglobulins and immune complexes (ICs). Our studies indicate that the major immunoglobulin (Ig) classes of IgG, IgM, and IgA specifically bind to three separate regions of the Fn molecule. To examine the biochemical nature and structure/function relationship of Fn/Ig interaction, we plan to determine the primary structure in both Ig's and Fn, involved in this interaction. This will be accomplished in two ways: 1) by obtaining proteolytic fragments of Fn and Igs, that retain their binding capacity, for amino acid sequencing. 2) by inhibiting the interaction of Fn with Igs in a competitive ELISA using genetically cloned amino acid sequences of Fn (type I repeat modules) and synthetic peptides of Fn and Igs. Because Fn is an opsonin, the significance of Fn/Ig interaction is implicated in accelerated clearance of ICs from the circulation and at sites of deposition. From a pathological consideration, the interaction of Fn with Ig may be involved in the etiology of immune complex disease (ICD), such as observed in many myeloproliferative and autoimmune disorders, where inflammation results from the deposition of ICs in tissues that contain Fn. We plan to compare the binding interaction (affinities) of Fn with normal Igs and cryoglobulins, by ELISA, and determine whether a minimum aggregate size of Ig complex may dispose the binding of ICs to Fn. Fn-containing extracellular matrices (ECM) will be generated (acellular following cell lysis) and used as an in vitro model to test for IC binding; this system should provide an in vivo correlate for IC deposition in tissues. The Ig-binding peptide sequence of Fn, determined by the structural studies, will be use to inhibit ICs from binding to the ECM. Effective inhibition would demonstrate a role for ECM Fn (tissue) in the sequestration of ICs and thereby, implicate the interaction of Fn with Ig in the mechanism of ICD. The study of the interaction of Fn with Ig should provide insight into the etiology of ICDs and elucidate mechanisms involved in normal host immune function.