Antibodies to secretogranin II reveal potential processing sites.

Several events occur during secretory granule maturation in endocrine and neuronal cells, one of the most important being the processing of prohormones. In addition, secretory granules undergo several changes during storage and maturation within the cell. We have been investigating the maturation of secretory granules in the neuroendocrine cell line PC12. Our working hypothesis postulates that fusion of newly budded secretory granules occurs during maturation and results in a larger secretory granule. We have been investigating the kinetics and specificity of the prohormone processing enzymes towards secretogranin II. Processing of secretogranin II must occur predominantly in the maturing secretory granule and could be used as a method to monitor secretory granule maturation.