IGE BINDING PROTEIN--A MULTIFUNCTIONAL ANIMAL LECTIN

本项目的重点是IgE结合蛋白（epsilon-BP）， 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）细胞中鉴定出31，000 Mr蛋白， 现在已知的是可溶性凝集素，其他人用不同的名称命名 实验室，似乎有多种功能。 该蛋白质具有 广泛的组织分布，在细胞表面发现，也分泌 在某些条件下。 Epsilon-BP具有特异性， 具有末端半乳糖的寡糖结构未被 唾液酸和它的功能至少是双磷酸。 除了 结合IgE，ε-BP结合各种细胞类型的表面， 包括肥大细胞。 首先，epsilon-BP多价性的分子基础将是 阐明。 我们有证据表明，ε-BP有一种倾向， 通过分子间的相互作用，包括氨基， 末端结构域，产生二聚体或寡聚体。 的这种性质 ε-BP将进一步研究，包括平衡 超离心分析和与乳糖基-琼脂糖4 B的结合 含有不同密度的乳糖。 的另一个解释 epsilon-BP的二价是通过一个二聚体的形成。 分子间二硫键。 的分子机制， 将研究ε-BP的共价二聚化。 第二，细胞表面糖蛋白配体的ε-BP将是 鉴定 初步研究表明，ε-BP附着在 肥大细胞表面的糖缀合物和只有少量的 RBL细胞表面上的不同糖蛋白种类被 ε-BP 值得注意的是，这些糖蛋白之一是高 亲和力IgE受体（Fc-IgE-RI）。 我们将专注于隔离， 另一种ε-BP反应性Mr 150，00糖蛋白的表征。 然后，我们将研究ε-BP识别的可能变化， 在不同分化阶段的肥大细胞上的FC-β-RI，或 激活状态。 第三，ε-BP作为多功能调节剂分子的功能 将建立。 证明了ε-BP的多价性 细胞表面糖蛋白的性质和识别，特别是 Fc-γ-RI，我们认为这种凝集素具有调节 这些糖蛋白介导的肥大细胞的细胞功能。 我们 已经表明，ε-BP增强了Fc-γ-RI介导的 肥大细胞活化 我们将进一步证实这种调制器的作用 的epsilon-BP和调查机制所观察到的增强 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.