Brewer C F
Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10641, USA.
Adv Exp Med Biol. 2001;491:17-25. doi: 10.1007/978-1-4615-1267-7_2.
The present findings provide a molecular basis for a new paradigm of specificity in multivalent carbohydrate-lectin interactions, namely the formation of type 2 homogeneous cross-linked lattices between multivalent carbohydrates and lectins. The present x-ray data demonstrate that the cross-linked complexes formed between a series of structurally related divalent carbohydrates and a single tetravalent lectin (SBA) are distinct and due to crystal packing interactions. These results thus provide a molecular basis for the formation of homogeneous type 2 cross-linked complexes between lectins and multivalent carbohydrates and glycoconjugates. These findings are also relevant to the observations that lectin-carbohydrate cross-linking interactions are involved in cellular recognition and signal transduction processes. For example, activated human T-cells undergo apoptosis due to binding and cross-linking of specific glycoprotein receptors by galectin-1 (Pace et al., 1999). Confocal microscopy shows that the galectin cross-linked glycoprotein receptors form homogeneous aggregates from a population of previously dispersed molecules on the surface of the cells. The crystal structures of the four SBA/pentasaccharide complexes thus repesent models for lectin-carbohydrate clustering in vivo.
目前的研究结果为多价碳水化合物-凝集素相互作用中特异性的新范式提供了分子基础，即多价碳水化合物和凝集素之间形成2型均匀交联晶格。目前的X射线数据表明，一系列结构相关的二价碳水化合物与单一四价凝集素（SBA）之间形成的交联复合物是不同的，且是由晶体堆积相互作用导致的。因此，这些结果为凝集素与多价碳水化合物和糖缀合物之间形成均匀的2型交联复合物提供了分子基础。这些发现也与凝集素-碳水化合物交联相互作用参与细胞识别和信号转导过程的观察结果相关。例如，活化的人类T细胞由于半乳糖凝集素-1与特定糖蛋白受体的结合和交联而发生凋亡（Pace等人，1999年）。共聚焦显微镜显示，半乳糖凝集素交联的糖蛋白受体从细胞表面先前分散的分子群体中形成均匀的聚集体。因此，四种SBA/五糖复合物的晶体结构代表了体内凝集素-碳水化合物聚集的模型。
