IGE BINDING PROTEIN--A MULTIFUNCTIONAL ANIMAL LECTIN

这个项目的重点是IgE结合蛋白(epsilon-BP)和 强调其对肥大细胞功能的调节作用。Epsilon-BP是一种 在大鼠嗜碱性白血病(RBL)细胞中发现31,000个MR蛋白 现在被称为可溶性凝集素，有不同的名字 实验室，似乎有多种功能。这种蛋白质有 组织分布广泛，见于细胞表面，也可分泌 在某些情况下。Epsilon BP对DISTINCT具有特异性 具有未被掩蔽的末端半乳糖的寡糖结构 唾液酸，它的功能至少是二价的。除了……之外 结合IgE，epsilon-BP结合到各种细胞类型的表面， 包括肥大细胞。 首先，epsilon-BP多价的分子基础将是 已澄清。我们有证据表明，epsilon-BP有一种倾向 通过涉及氨基的分子间相互作用自结合-- 末端结构域，产生二聚体或低聚物。的这一属性 将对Epsilon-BP进行进一步研究，包括平衡 超速离心分析及其与乳糖基琼脂糖凝胶4B的结合 含有不同密度的乳糖。另一种解释是 Epsilon-BP的二价态是通过一种 分子间二硫键。人类免疫缺陷的分子机制 将研究epsilon-BP的共价二聚反应。 第二，细胞表面糖蛋白配基为epsilon-BP 已确认身份。初步研究表明，epsilon-BP与 肥大细胞表面有糖偶联物，仅有少量 RBL细胞表面不同糖蛋白的识别 Epsilon-BP。值得注意的是，其中一种糖蛋白是高 亲和力IgE受体(Fc-epsilon-RI)。我们将重点关注孤立和 另一种epsilon-BP反应性MR 150，00糖蛋白的特性。 然后，我们将研究epsilon-BP识别的可能变异 肥大细胞不同分化阶段Fc-epsilon-RI的表达 激活状态。 第三，epsilon-BP作为多功能调节剂分子的功能 将会建立起来。已经证明了epsilon-BP的多价 细胞表面糖蛋白的性质和识别，尤其是 Fc-epsilon-RI，我们认为该凝集素具有调节 这些糖蛋白介导的肥大细胞的细胞功能。我们 已经证明epsilon-BP增强Fc-epsilon-RI介导的 肥大细胞激活。我们将进一步证实这种调节作用。 并探讨观察到的增强作用的机制 效果。

The focus of this project is on IgE-binding protein (epsilon-BP) with emphasis on its modulatory role on mast cell functions. Epsilon-BP is a 31,000 Mr protein identified in rat basophilic leukemia (RBL) cells and is now known as soluble lectin designated with different names by other laboratories and appears to have multiple functions. The protein has wide tissue distribution, is found on the cell surface and also secreted under certain conditions. Epsilon-BP has specificity for distinct oligosaccharide structures that have a terminal galactose not masked by sialic acids and it functions at least bivalently. In addition to binding IgE, epsilon-BP binds to surfaces of various cell types, including mast cells. First, the molecular basis for multivalency of epsilon-BP will be elucidated. We have evidence that epsilon-BP has a tendency to self-associate through intermolecular interactions involving the amino-- terminal domain, resulting in dimers or oligomers. This property of epsilon-BP will be further investigated, including equilibrium ultracentrifugation analysis and binding to lactosyl-Sepharose 4B containing varying densities of lactose. Another explanation for bivalency of epsilon-BP is the formation of a dimer through an inter-molecular disulfide linkage. The molecular mechanism for the covalent dimerization of epsilon-BP will be investigated. Second, cell surface glycoprotein ligands for epsilon-BP will be identified. Preliminary studies indicate that epsilon-BP is attached to glycoconjugates on the surface of mast cells and only a small number of different glycoproteins species on RBL cell surface are recognized by epsilon-BP. Significantly, one of these glycoproteins is the high affinity IgE receptor (Fc-epsilon-RI). We will focus on isolation and characterization of another epsilon-BP-reactive Mr 150,00 glycoprotein. We will then investigate possible variation in epsilon-BP recognition of FC-epsilon-RI on mast cells at various differentiation stages or activation status. Third, the function of epsilon-BP as a multifunctional modulator molecule will be established. Having demonstrated epsilon-BP's multivalent property and recognition of cell surface glycoproteins, especially Fc-epsilon-RI, we propose that this lectin has the potential to modulate cellular functions of mast cells mediated by these glycoproteins. We have already shown that epsilon-BP potentiates Fc-epsilon-RI-mediated mast cell activation. We will further substantiate this modulator role of epsilon-BP and investigate the mechanism for the observed potentiating effect.