Protein synthesis in rat pancreas: II. Changes in the intracelluar distribution of pancreatic amylase during the secretory cycle

Changes in the intracellular distribution of amylase and in the biochemical properties of the microsome and supernatant fluid fractions of rat pancreas have been studied during a complete secretory cycle. In general, the amylase activity reached a minimum about two hours after the injection of pilocarpine returning gradually to normal at about eight hours after the injection. The most extensive early loss of amylase activity occurred in the secretory granules; the smallest relative loss occurred in the microsome fraction. Essentially no change was observed in the protein, ribose nucleic acid or phospholipid of the microsome and supernatant fluid fractions, but extensive changes were observed in the quantity of secretory granule material. Apparently the structural components of the microsome and supernatant fluid fractions are conserved throughout the secretory cycle, while the substance of the secretory granules undergoes marked changes in quantity.