Galectins are a family of carbohydrate-binding proteins that share a conserved sequence and affinity for beta-galactosides. Some, such as galectin-1, are isolated as dimers and have a single carbohydrate recognition domain (CRD) in each monomer, whereas others, The new galectin, galectin-6, lacks a 24-amino acid stretch in the link region between the two CRDs that is present in galectin-4. Otherwise, these two galectins have 83% amino acid identity.

Expression of both galectin-4 and galectin-6 is confined to the epithelial cells of the embryonic and adult gastrointestinal tract. Galectin-4 is expressed at about equal levels in colon and small intestine but much less in stomach, whereas galectin-6 is expressed at about equal levels throughout the gastrointestinal tract.