Triticum vulgaris (Wheat) Lectin (WGA)
Wheat germ agglutinin (WGA) is isolated from wheat germ (Triticum vulgaris) and is a protein that reversibly and non-enzymatically binds to N-acetyl-D-glucosamine and sialic acid residues of glycoproteins and glycolipids. This lectin protects Triticum vulgaris from insects, yeast and bacteria. WGA consists of two subunits and has a molecular weight of 36 kDa. It is an acidic protein with an isoelectric point greater than pH 9. WGA has mitogenic activity toward lymphocytes. It agglutinates erythrocytes (rabbit erythrocytes at less than 0.1 µg/ml following trypsin treatment of the cells) and most types of malignant cells.
Studies show that WGA is very effective in enhancing the rate of glucose oxidation in isolated fat cells (maximal effects similar to that achieved with insulin). Studies also report that this lectin inhibits C5a receptor interaction, which has the implications of receptor micro-heterogeneity and ligand binding sites.
Native WGA has also been reported to interact with some glycoproteins via sialic acid residues (succinylated WGA). This lectin is used for the purification of insulin receptors and for neuronal tracing.