33 - Excitation-Secretion Coupling

Abstract

Publisher Summary This chapter explains that the first step in the secretory process for peptide hormones and neurotransmitters involves synthesis, modification, and sorting of the molecules to be secreted. These secretory molecules are packaged in secretory granules or vesicles, which are then transported to the cell periphery, where they are released in the extracellular space by fusion with the plasma membrane. This complex process is named exocytosis. Interaction of cytoskeletal structures with transmembrane signaling is an important feature of the excitation–secretion coupling. Actin-binding proteins are in large part responsible for cytoskeleton–receptor interactions. Dynamic changes in the cytoskeletal network are required for exocytosis. The subplasmalemmal area of secretory cells is characterized by the presence of a highly organized cytoskeletal network. The chapter also discusses that in regulated exocytosis, fusion of secretory granules with the plasma membrane is triggered by an appropriate signal. Whenever a secretory granule fuses with the plasma membrane, the total capacitance of the cell increases by a value proportional to the surface area of the new membrane added to the existing cell membrane.