The chromaffin granule surface. Localization of carbohydrate on the cytoplasmic surface of an intracellular organelle.

Intact chromaffin granules from bovine adrenal medulla are shown to have complex carbohydrates on their external (cytoplasmic) surface. This is demonstrated by the facts (1) that granules can be agglutinated by wheat germ agglutinin, and (2) that significant amounts of sialic acid can be removed from the granule surface with neuraminidase. Glycoproteins located in the granule membrane, and not glycolipids, are the molecules that mediate wheat germ agglutinin agglutination. The possible involvement of granule surface carbohydrate in the process of exocytosis is discussed.