Bardosi A, Bardosi L, Hendrys M, Wosgien B, Gabius H J
Institute of Pathology, Academic Hospital of University of Münster, Federal Republic of Germany.
Am J Anat. 1990 Aug;188(4):409-18. doi: 10.1002/aja.1001880409.
Protein-carbohydrate recognition may be involved in an array of molecular interactions on the cellular and subcellular levels. To gain insight into the role of proteins in this type of interaction, surgically removed specimens of human endomyocardial tissue were processed for histochemical and biochemical analysis. The inherent capacity of these sections to bind individual sugar moieties, which are constituents of the carbohydrate part of cellular glycoconjugates, was assessed using a panel of biotinylated neoglycoproteins according to a standardized procedure. Together with appropriate controls, it primarily allowed localization of endogenous lectins. Differences in lectin expression were observed between layers of endocardial tissue, myocardial cell constituents, connective-tissue elements, and vascular structures. The endocardium proved to be positive with beta-galactoside-bearing probes; with neoglycoproteins carrying beta-xylosides, alpha-fucosides, and galactose-6-phosphate moieties; and with probes containing a carboxyl group within the carbohydrate structure, namely sialic acid and glucuronic acid. In contrast, only fucose-and maltose-specific receptors were apparent in the elastic layers of the endocardium. Aside from ascertaining the specificity of the protein-carbohydrate interaction by controls, i.e., lack of binding of the probe in the presence of the unlabelled neoglycoprotein and lack of binding of the labelled sugar-free carrier protein, respective sugar receptors were isolated from heart extracts by using histochemically effective carbohydrates as immobilized affinity ligand. Moreover, affinity chromatography using immobilized lactose as affinity ligand as well as the use of polyclonal antibodies against the predominant beta-galactoside-specific lectin of heart demonstrated that the lactose-specific neoglycoprotein binding was due to this lectin. Remarkably, the labelled endogenous lectin, preferred to plant lectins for detecting ligands of the endogenous lectin, localized ligands in tissue parts where the lectin itself was detected glycohistochemically as well as immunohistologically. This demonstration of receptor-ligand presence in the same system is a further step toward functional assignment of the recorded protein-carbohydrate interaction. Overall, the observed patterns of lectin expression may serve as a guideline to elucidate the precise physiological relevance of lectins and to analyze pathological conditions comparatively.
蛋白质 - 碳水化合物识别可能涉及细胞和亚细胞水平上的一系列分子相互作用。为深入了解蛋白质在这类相互作用中的作用，对手术切除的人心内膜组织标本进行了组织化学和生化分析。根据标准化程序，使用一组生物素化的新糖蛋白评估这些切片结合单个糖部分的内在能力，这些糖部分是细胞糖缀合物碳水化合物部分的组成成分。连同适当的对照一起，这主要使得能够定位内源性凝集素。在内膜组织层、心肌细胞成分、结缔组织元件和血管结构之间观察到凝集素表达的差异。心内膜被证明对带有β - 半乳糖苷的探针呈阳性；对携带β - 木糖苷、α - 岩藻糖苷和6 - 磷酸半乳糖部分的新糖蛋白呈阳性；对碳水化合物结构内含有羧基的探针，即唾液酸和葡萄糖醛酸呈阳性。相比之下，仅在内膜的弹性层中可观察到岩藻糖和麦芽糖特异性受体。除了通过对照确定蛋白质 - 碳水化合物相互作用的特异性，即在未标记的新糖蛋白存在下探针不结合以及标记的无糖载体蛋白不结合之外，还通过使用组织化学有效的碳水化合物作为固定化亲和配体从心脏提取物中分离出各自的糖受体。此外，使用固定化乳糖作为亲和配体的亲和色谱以及针对心脏主要的β - 半乳糖苷特异性凝集素的多克隆抗体表明，乳糖特异性新糖蛋白结合是由于这种凝集素。值得注意的是，标记的内源性凝集素比植物凝集素更适合检测内源性凝集素的配体，它在通过糖组织化学以及免疫组织化学检测到凝集素本身的组织部位定位配体。在同一系统中证明受体 - 配体的存在是朝着对所记录的蛋白质 - 碳水化合物相互作用进行功能分配迈出的又一步。总体而言，观察到的凝集素表达模式可作为阐明凝集素精确生理相关性以及比较分析病理状况的指导。
