Wheat germ agglutinin
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[1] and cornea[2] 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.
See also
- Proteopedia: 2uvo - High resolution crystal structure of Wheat Germ Agglutinin in complex with N-acetyl-D-glucosamine
- Proteopedia: 2uwg - Crystal structure of Wheat Germ Agglutinin isolectin 1 in complex with glycosylurethan