Fig. 1.

A simplified schematic depicting agonist-induced endocytosis of GPCRs. Binding of an agonist results in activation of the receptor and coupling of heterotrimeric G proteins. This is followed by the phosphorylation of receptor tail (carboxyl-terminus) and recruitment of β-arrestins to the receptor. Subsequently, the receptor is internalized through the formation of clathrin coated vesicles which results in a decrease in receptor density at the cell surface.