Cells interaction with lectins

Su et al. 2005). Mannosyl lipid containing liposomes have also been used for this purpose (Zhang et al. 2005). The glycolipids are presumed to interact with lectins present on the surface of the bacterial cells. 

Selectins are a family of plasma membrane lectins that mediate cell-cell recognition and adhesion in a wide range of cellular processes. One such process is the movement of immune cells (T lymphocytes) through the capillary wall, from blood to tissues, at sites of infection or inflammation (Fig. 7-33). At an infection site, P-selectin on the surface of capillary endothelial cells interacts with a specific oligosaccharide of the glycoproteins of circu-... 

The chief function of lectins in animals is to facilitate cell-cell contact. A lectin usually contains two or more binding sites for carbohydrate units some lectins form oligomeric structures with multiple binding sites. The binding sites of lectins on the surface of one cell interact with arrays of carbohydrates displayed on the surface of another cell. Lectins and carbohydrates are linked by a number of relatively weak interactions that ensure specificity yet permit unlinking as needed. The interactions between one cell surface with carbohydrates and another with lectins resemble the action of Velcro each interaction is relatively weak but the composite is strong. 

Synthetic carbohydrate polymers, so-called glycopolymers, also exhibit specific interactions with lectins and proteins. Thus, synthetic polymers containing sugar units can mimic functions similar to those found in biological interactions of natural carbohydrates. Figure 5.18 schematically highlights possible interactions of glycopolymer architectures with cell membranes. 

The ability of PO to interact with the acetyl residues of chitin allows us to compare them with monovalent lectins (i.e. extensins) which when binding with hemicellulose are only affected in a medium with a high ionic strength (Brownleader et al., 2006). As a rule, POs are bound with the plant cell wall and act as its modifiers. Some POs can form complexes with an extensin of cell walls (Brownleader et al., 2006). Consequently, chitin-specific sites that are capable of interacting with polysaccharides exist in the molecules of PO, and these sites can resemble the membrane receptor binding sites or else be similar to the domains of heparinbinding proteins (Kim et al., 2001). 

Interact with specific carbohydrates Lectins, selectins (cell adhesion lectins), antibodies... 

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