Probing Cell Surface Lectins with Neoglycoconjugates

摘要

Lectins are expressed on various cells and are involved in numerous processes related to vital functions of organisms [1-4]. C-lectins, galectins-1 and -3, for example, are the counter receptors for integrins, whereas galectin-1, -3, siglec-1, -2 - for proteins of immune cells. Lectins mediate cell-cell and cell-matrix adhesion, cell proliferation, and apoptosis [2, 5, 6]. Selectins, galectin-3, and galectin-9 are inflammation mediators or chemoattractants [7]. Lectins expressed on macrophages, dendritic cells, and NK cells are involved in antitumor, antimicrobial, and antiviral protection of the organism [6, 8-10]. Knowledge of carbohydrate-binding properties of cell surface lectins is important for understanding their functions. At the same time revealing cell lectins and studying their specificity are associated with a number of difficulties. Firstly, the same lectins can be exposed not only on cell membrane surface but also be localized inside the cell. Secondly, different lectins can recognize similar carbohydrate ligands in probe composition. Thirdly, lectins expressed on the cell surface can be masked with the glycoconjugates of the same cells (cis-interaction) [11, 12], and therefore not bind external ligands, including probes. Finally, lectin topography on the cell affects its binding with carbohydrate probes.