STRUCTURE AND FUNCTION OF THE HIGH AFFINITY IGE RECEPTOR

免疫球蛋白E特异性高亲和力受体（Fc ε RI） (IgE)主要存在于肥大细胞和嗜碱性粒细胞上。 激活这些 细胞对Fc ε RI与IgE-抗原的交联产生反应 复合物，其启动细胞事件的级联，最终在 释放的有毒物质，有助于 许多特应性疾病如变态反应、过敏性 哮喘和速发型超敏反应。 在这项研究计划中， 有助于特异性受体Fc γ RI的结构特征 功能将被探索。 目标之一是确定 参与IgE结合的Fc β RI α亚基的表达。 这将是 （i）蛋白质工程研究 使用结构域和点诱变方法，和（ii）结构 初步使用核磁共振进行的说明研究 共振光谱学在一项合作研究中与A。Bax，国家 卫生研究院。 一个平行的，但更长期的目标是， 受体片段晶体适合于最终的晶体学研究。 蛋白质工程研究将广泛利用强大的 噬菌体展示结合细菌表达Fc技术 α-干扰素受体α片段，随后进行物理表征 配体结合活性。 这项研究的一个长期目标是精确的 Fc的“最小复合物”的三维构型的定义 α-IgE。 另一个优先级较低的目标是， 建议通过以下方法表征大鼠α亚基胞外域： 详细的蛋白质工程研究，最终目标是 阐明了该IgE结合分子的三维结构。 的 Fc β RI β和/或γ亚基共表达的要求 将探索大鼠-人α链胞外域嵌合体作为一种手段， 探测假定的受体的细胞外相互作用 亚单位。 所有这些研究的进展应该有助于合理的 设计用于治疗特应性疾病的潜在治疗剂。 此外，研究结果还将有助于其他基因的分子研究。 免疫重要受体[如Fc γ R]， 预期与IgE肥大细胞共享重要的结构特征 受体的

The high-affinity receptor (Fc epsilon RI) specific for immunoglobulin E (IgE) is found primarily on mast cells and basophils. Activation of these cells occurs in response to crosslinking of Fc epsilon RI with IgE-antigen complexes which initiates a cascade of cellular events culminating in the release of pharmacologically active substances that contribute to the clinical symptoms of many atopic disorders such as allergy, allergic asthma and immediate hypersensitivity. In this research program the structural features of Fc epsilon RI that contribute to specific receptor function will be explored. One goal is to define the molecular features of the Fc epsilon RI alpha-subunit involved in IgE binding. This will be approached using the dual approach of (i) protein engineering studies using both domain and point mutagenesis procedures and (ii) structure elucidation studies to be conducted initially using nuclear magnetic resonance spectroscopy in a collaborative study with Dr. A. Bax, National Institutes of Health. A parallel, but longer-term goal, is to generate receptor fragment crystals suitable for eventual crystallographic studies. Protein engineering studies will extensively utilize the powerful technique of phage display together with bacterial expression of Fc epsilon RI alpha fragments with subsequent physical characterization of ligand-binding activity. A long-term goal of this study is the precise definition of the 3-dimensional configuration of a "minimum complex" of Fc epsilon RI alpha-IgE. An additional but lower priority aim of this Proposal is to characterize the rat alpha-subunit ectodomain through detailed protein engineering studies, with the eventual goal of elucidating the 3-dimensional structure of this IgE-binding molecule. The requirement for Fc epsilon RI beta and/or gamma-subunit coexpression for rat-human alpha-chain ectodomain chimera will be explored as a means of probing the presumptive extracellular interaction of the receptor subunits. Progress in all of these studies should assist in the rational design of potential therapeutics for the treatment of atopic disorders. In addition, results should facilitate molecular studies of other immunologically important receptors [such as Fc gamma R] which are expected to share significant structural features with the IgE mast cell receptor.