Wheat germ agglutinin or WGA is a lectin that protects wheat (Triticum vulgaris) from insects, yeast and bacteria. An agglutinin protein, it binds to N-acetyl-D-glucosamine and Sialic acid. N-acetyl-D-glucosamine in the natural environment of wheat is found in the chitin of insects, and the cell membrane of yeast & bacteria. WGA is found abundantly—but not exclusively—in the wheat kernel, where it got the 'germ' name from. In mammals the N-acetyl-D-glucosamine that WGA binds to is found in cartilage and cornea among other places. In those animals sialic acid is found in mucous membranes, e.g. the lining of the inner nose, and digestive tract.
In solution, WGA exists mostly as a heterodimer of 38,000 daltons. It is cationic at physiological pH.