Identification of ligand specificities for glycan-binding proteins using glycan arrays

Protein-glycan interactions mediate diverse biological processes in cell communication and innate immunity. They involve the binding of a protein on one cell surface to a glycosylated protein or lipid on an opposing cell surface. Understanding the functional significance of these interactions is of major interest to the scientific community. Numerous studies have demonstrated the utility of solid-phase glycan arrays as a means of identifying glycan binding specificity. These approaches share a common format in that glycans are attached in some manner to a solid-phase surface and the glycan-binding protein (GBP) is presented in solution for binding analysis. Multiple options are available to investigators for detecting these interactions, but the most robust reporters are fluorescence based, and binding can be detected as relative fluorescence units. The solid-phase assays have been proved to be highly scalable and suitable for manufacturing processes. The latest innovations have led to the production of miniaturized arrays using microarray printing technology to produce glycan microarrays with the potential to spot and interrogate several thousands of unique glycans simultaneously. This chapter describes two glycan array platforms developed by the Consortium for Functional Glycomics, a microtiter plate-based array and a covalent printed array, and the analytic methods used to conduct binding specificity assays for a broad range of GBPs and organisms.