A phosphorylation cascade initiated by the activation of the serotonin GPCR by the Lysergic Acid Diethylamide ligand. The result of this cascade is dynamic alteration of the cytoskeleton, causing the growth and reorganization of synapses, changes in gene expression, and the alteration of patterns cellular metabolism.
This illustration shows a synapse. When an action potential arrives at a synapse, the positive charge causes the opening of voltage gated calcium channels. Calcium pours into the synaptic button and binds to several proteins, changing their shape. The activated proteins dynamically rearrange the blue cytoskeleton to transport green vesicles filled with yellow neurotransmitters to the synaptic cleft, which is filled with red adhesion proteins. Calcium-activated SNARE proteins bind to both the vesicle and the synaptic membrane, causing the vesicle to fuse with the membrane, turning it inside out and spilling neurotransmitters into the synaptic cleft. The neurotransmitters then bind to proteins on the receiving cell. There are several types of yellow-green receptor proteins. Sodium (Na+) channels (excitatory) respond the the neurotransmitter Glutamate. Chloride (Cl-) channels (inhibitory) respond to the neurotransmitter GABA. Dopamine, Serotonin, and Opioids bind to G-Protein Coupled Receptors (GPCRs) which cause complicated phosphorylation cascades that change the metabolism of the cell.
A cross section through a synapse. The synaptic button is green, the insulating glial cell is purple, and the receiving muscle fiber is red. The synaptic cleft is the thin space between the synaptic button and and the muscle fiber. Dark blue circles in the synaptic button are mitochondria, and the small green circles are vesicles filled with yellow neurotransmitters.