Weis W I, Taylor M E, Drickamer K
Department of Structural Biology, Stanford University School of Medicine, California, USA.
Immunol Rev. 1998 Jun;163:19-34. doi: 10.1111/j.1600-065x.1998.tb01185.x.
Protein-carbohydrate interactions serve multiple functions in the immune system. Many animal lectins (sugar-binding proteins) mediate both pathogen recognition and cell-cell interactions using structurally related Ca(2+)-dependent carbohydrate-recognition domains (C-type CRDs). Pathogen recognition by soluble collections such as serum mannose-binding protein and pulmonary surfactant proteins, and also the macrophage cell-surface mannose receptor, is effected by binding of terminal monosaccharide residues characteristic of bacterial and fungal cell surfaces. The broad selectivity of the monosaccharide-binding site and the geometrical arrangement of multiple CRDs in the intact lectins explains the ability of the proteins to mediate discrimination between self and non-self. In contrast, the much narrower binding specificity of selectin cell adhesion molecules results from an extended binding site within a single CRD. Other proteins, particularly receptors on the surface of natural killer cells, contain C-type lectin-like domains (CTLDs) that are evolutionarily divergent from the C-type lectins and which would be predicted to function through different mechanisms.
蛋白质-碳水化合物相互作用在免疫系统中发挥多种功能。许多动物凝集素（糖结合蛋白）利用结构相关的依赖钙离子的碳水化合物识别结构域（C型CRD）介导病原体识别和细胞间相互作用。血清甘露糖结合蛋白和肺表面活性物质蛋白等可溶性物质以及巨噬细胞表面甘露糖受体对病原体的识别，是通过结合细菌和真菌细胞表面特有的末端单糖残基来实现的。单糖结合位点的广泛选择性以及完整凝集素中多个CRD的几何排列解释了这些蛋白质介导自我与非自我区分的能力。相比之下，选择素细胞粘附分子更狭窄的结合特异性源于单个CRD内的延伸结合位点。其他蛋白质，特别是自然杀伤细胞表面的受体，含有与C型凝集素在进化上不同的C型凝集素样结构域（CTLD），预计其通过不同机制发挥作用。
