Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, University of California, Los Angeles, California 90095; email:
Annu Rev Immunol. 2016 May 20;34:243-64. doi: 10.1146/annurev-immunol-041015-055402. Epub 2016 Feb 22.
Galectins are a family of mammalian carbohydrate-binding proteins expressed by many cell types. Galectins can function intracellularly and can also be secreted to bind to cell surface glycoconjugate counterreceptors. Some galectins are made by immune cells, whereas other galectins are secreted by different cell types, such as endothelial or epithelial cells, and bind to immune cells to regulate immune responses. Galectin binding to a single glycan ligand is a low-affinity interaction, but the multivalency of galectins and the glycan ligands presented on cell surface glycoproteins results in high-avidity binding that can reversibly scaffold or cluster these glycoproteins. Galectin binding to a specific glycoprotein counterreceptor is regulated in part by the repertoire of glycosyltransferase enzymes (which make the glycan ligands) expressed by that cell, and the effect of galectin binding results from clustering or retention of specific glycoprotein counterreceptors bearing these specific ligands.
半乳糖凝集素是一类哺乳动物糖结合蛋白，许多细胞类型都表达半乳糖凝集素。半乳糖凝集素可以在细胞内发挥作用，也可以分泌出来与细胞表面糖缀合物的受体结合。一些半乳糖凝集素由免疫细胞产生，而其他半乳糖凝集素则由不同类型的细胞分泌，如内皮细胞或上皮细胞，并与免疫细胞结合，以调节免疫反应。半乳糖凝集素与单个糖配体的结合是一种低亲和力的相互作用，但半乳糖凝集素的多价性和细胞表面糖蛋白上呈现的糖配体导致了高亲和力的结合，这种结合可以可逆地支架或聚集这些糖蛋白。半乳糖凝集素与特定糖蛋白受体的结合部分受到该细胞表达的糖基转移酶酶谱（产生糖配体）的调节，而半乳糖凝集素结合的效果则来自于带有这些特定配体的特定糖蛋白受体的聚类或保留。
