Beta-arrestin-1 (ARRB1)

During homologous desensitization, beta-arrestins bind to the GPRK-phosphorylated receptor and sterically preclude its coupling to the cognate G- protein; the binding seems to require additional receptor determinants exposed only in the active receptor conformation. The beta-arrestins target many receptors for internalization by behaving as endocytic adapters (CLASPs, clathrin-associated sorting proteins) and recruitment the GPRCs into the adapter protein 2 complex 2 (AP-2) in clathrin-coated pits (CCPs).

However, the degree of beta-arrestin involvement seems to vary significantly depending on the receptor, agonist and cell type. Internalized arrestin-receptor complexes traffic to intracellular endosomes, where they remain uncoupled from G-proteins.