FAST RESENSITIZATION OF G PROTEIN-COUPLED RECEPTORS REQUIRES THEIR PI(4,5)P₂-DEPENDENT SORTING INTO AN AP2 POSITIVE...

G protein coupled receptors (GPCRs) are the target of about 35% of FDA-approved drugs, which underlines their importance in physiology and disease. Many GPCRs undergo rapid desensitization upon agonist activation, mediated by β-arrestin binding to the phosphorylated receptors, which prevents their G protein coupling. How such receptors regain their G protein signaling competence is poorly understood. Using the AT1 angiotensin II receptor (AT1R), we show that its rapid re-sensitization requires the sorting of the receptors into an AP2-positive plasma membrane (PM) compartment without receptors having to be internalized. This process requires the scaffolding protein, EFR3 and a dedicated PI(4,5)P ₂ pool specifically produced by PIP5KA. While β-arrestin 1 and -2 both can carry the receptors to the AP2 compartment, weaker binding of β-arrestin 1 to the receptor allows some of the receptors to re-sensitize, while strong β-arrestin 2 binding elicits stronger desensitization and directs the receptors for internalization. These results suggest that the rapid phase of re-sensitization of GPCRs occurs without their endocytosis and primarily takes place at the PM at specific steps during clathrin-coated pit maturation. Together with differences observed between the two β-arrestins to interact with CCPs and the receptors, our data suggest that specific PI(4,5)P ₂ pools controlled by EFR3A and PIP5K1A determine the balance between β-arrestin1 and -2 receptor interaction and delivery to the AP2 positive compartment, ultimately determining what fraction of the receptors regain their G protein signaling competence.