Answer to Question #198584 in Cell Biology for Rosalia

Question

what would happen if each vesicle does not fuse with the plasma membrane

Answer 1

These vesicles do not fuse with the plasma membrane once they arrive there, unlike the constitutive pathway; they are carried by microtubules on the cells' cytoskeleton to near the surface of the membrane. The vesicles only fuse with the membrane once they receive a signal from a receptor after a messenger (e.g. a hormone) has successfully bonded to the receptor. This complex activates intracellular signals that cause the vesicles to fuse with the membrane and release their contents into the environment. A good example is in nerve cells in the pre-synaptic membrane, when an action potential reaches the pre-synaptic membrane and causes a flow of calcium ions into the cell, these ions then allow the vesicles to fuse with the membrane and release their contents; in the case with neurons it is usually neurotransmitters such as acetylcholine and dopamine released^[5].