Figure 8

Various receptor signaling and regulatory pathways. (A) Receptor activation by agonist leads to rapid phosphorylation, interaction with β-arrestin and sequestration into clathrin-coated pits. Coated pits containing the receptors pinch off the plasma membrane into intracellular vesicles. Internalized receptors are then de-phosphorylated and recycled back to the cell surface for further stimulation or are routed to the lysosomes for degradation (down-regulation). (B) Following treatment with some agonists it is possible that receptors do not recycle back to the surface, implying that these receptors remain sequestered and continue to signal before being routed to the lysosomes for degradation.