Immunological characterization of a membrane glycoprotein of chromaffin granules: its presence in endocrine and exocrine tissues.

A glycoprotein was isolated from detergent solubilized membranes of bovine chromaffin granules by high-performance liquid chromatography. Specific antisera raised against this glycoprotein reacted in one- and two-dimensional immunoblots with a heterogeneous component with a pI of 4.2-4.7 and Mr 100,000. The antiserum against bovine glycoprotein II cross-reacted with an analogous component in several species. The specific localization of glycoprotein II in chromaffin granules was established by density gradient centrifugation followed by immunoblotting. The antiserum, as shown by one- and two-dimensional immunoblotting, reacted with an analogous antigen in the posterior pituitary, in endocrine (anterior pituitary, parathyroid gland) and exocrine (parotid gland, pancreas) organs. In the pancreas the protein reacting with the antiserum was found in the membranes of zymogen granules. The results demonstrate for the first time that secretory vesicles of endocrine and exocrine tissues have at least one common antigen, i.e. the glycoprotein II. It seems likely that this protein is involved in a basic function common to all secretory vesicles.