Insulin is secreted from pancreatic β-cells, and the high demand of insulin biosynthesis is known to cause β-cell dysfunction in patients with type 2 diabetes mellitus. The insulin biosynthetic pathway has been extensively studied and is still an exciting area for future studies. In this chapter, first, we focus on proinsulin biosynthetic pathway in the endoplasmic reticulum (ER) and recent progress of our knowledge about ER stress. We discuss about how ER stress is involved in the development of diabetes. Second, we focus on the formation of insulin secretory granules. The biogenesis of secretory granules has been explored for several decades; however, it still has been debated and has yet to be understood. We review the current knowledge about the secretory granules and discuss about the problems for future studies.
Part of the book: Ultimate Guide to Insulin