Chapter 25 Membrane Recycling in Secretory Cells: Implications for Traffic of Products and Specialized Membranes within the Golgi Complex

Abstract

Publisher Summary This chapter discusses the existence of considerable membrane recycling involving the Golgi and lysosomal elements in secretory cells. The results provide new information on the traffic of membranes and products through the Golgi complex. Evidence obtained on several glandular cell types using electron-dense tracers that points to the existence of recycling of granule membranes as containers for secretory products is presented in the chapter. According to the current concepts, to traverse the Golgi complex, membranes and products follow a unidirectional course from the rough endoplasmic reticulum (ER) to cis Golgi cisternae, to trans Golgi cisternae, and finally to plasmalemma. The existence of a pathway from the cell surface to the Golgi complex has a number of important implications. It provides a route whereby informational molecules (hormones, catecholamines, and other agents) from the extracellular environment can reach a biosynthetic compartment and thereby influence additional intracellular events. A mechanism where surface membrane components (receptors, enzymes, and other membrane proteins) could be modified (reglycosylated, sulfated, and phosphorylated) in passage through the Golgi complex is also discussed in the chapter.