Oligosaccharide and carbohydrate-binding protein arrays. (a) Oligosaccharide microarrays are used to detect and characterize carbohydrate-binding proteins. They are constructed by (1) spotting known oligosaccharides (either synthetic or naturally isolated) onto a solid surface such as a treated glass slide in a predetermined array. Whole cells can be bound to the array (2), but it is more common to first fractionate cells or tissues to isolate (3) putative carbohydrate-binding proteins. (b) Arrays of known carbohydrate-binding proteins (either lectins or monoclonal antibodies) are used to detect and characterize oligosaccharides. They are produced by printing spots of the proteins onto a suitable surface (1). Again, whole cells (2) can be bound to the array, but more usually (3) their cell-surface oligosaccharides will be isolated and used. Both types of array can be used for a variety of purposes.