Beta-arrestins function in regulating agonist-mediated G-protein coupled receptor (GPCR) signaling by mediating both receptor desensitization and resensitization processes. During homologous desensitization, beta-arrestins bind to the GPRK-phosphorylated receptor and sterically preclude its coupling to the cognate G-protein. Beta-arrestin binding appears to require additional receptor determinants exposed only in the active receptor conformation. The beta-arrestins target many receptors for internalization by acting as endocytic adapters (CLASPs, clathrin-associated sorting proteins) and recruiting the GPRCs to the adaptor protein 2 complex 2 (AP-2) in clathrin-coated pits (CCPs). This antibody recognizes beta-arrestin-1 and beta-arrestin-2. The extent of beta-arrestin involvement appears to vary significantly depending on the receptor, agonist and cell type.