Wheat germ agglutinin (WGA) contains a group of closely related isolectins, with an isoelectric point about pH 9. The receptor sugar for WGA is N-acetylglucosamine, with preferential binding to dimers and trimers of this sugar. WGA can bind oligosaccharides containing terminal N-acetylglucosamine or chitobiose, structures which are common to many serum and membrane glycoproteins. Bacterial cell wall peptidoglycans, chitin, cartilage glycosaminoglycans, and glycolipids can also bind WGA. Native WGA has also been reported to interact with some glycoproteins via sialic acid residues (see succinylated WGA). This lectin is used for the purification of insulin receptors and for neuronal tracing.