Part of “CHAPTER 3 – BIOSYNTHESIS AND SECRETION OF PEPTIDE HORMONES“

Much has been learned about the nature of polypeptide hormones and secretory granules.55,59,60 The hormones in this organelle are highly concentrated. In particular, a number of polypeptide hormones are condensed in a crystal lattice formation to increase the amount of hormone (up to 200-fold) in this organelle. Secretory granules allow cells to store enough hormone to be released on demand by extracellular signals at a level not possible by de novo synthesis. The t_1/2 of stored hormones may be days, whereas the t_1/2 of similar proteins in secretory vesicles may be minutes.