Adapter protein that plays a role in regulating cell-surface expression of adrenergic receptors and probably also other G protein-coupled receptors (PubMed:20559325, PubMed:21982743, PubMed:23208550). Plays a role in NEDD4-mediated ubiquitination and endocytosis af activated ADRB2 and subsequent ADRB2 degradation (PubMed:20559325, PubMed:23208550). May recruit NEDD4 to ADRB2 (PubMed:20559325). Alternatively, may function as adapter protein that does not play a major role in recruiting NEDD4 to ADRB2, but rather plays a role in a targeting ADRB2 to endosomes (PubMed:23208550). Interacts (via PPxY motifs) with NEDD4 (via WW domains) (PubMed:20559325, PubMed:23208550, PubMed:24379409). Interacts with ADRB2 (PubMed:20559325, PubMed:21982743, PubMed:25220262). Interacts with ADRB3 (PubMed:21982743). Interacts with HGS (via PPxY motifs) (PubMed:23208550). Does not bind TXN (thioredoxin) (PubMed:16269462). Interacts with ITCH (PubMed:23886940). Interacts with WWP1 (via WW domains) (PubMed:21191027). Associated with plasma membrane, as well as with endosomes and lysosomes during endocytosis (PubMed:16269462, PubMed:23208550, PubMed:20559325). Highly expressed in skeletal muscle, placenta, kidney, lung, liver, blood, adrenal gland, lymph node, mammary gland, thyroid, and trachea (PubMed:16269462, PubMed:21982743). Very low levels in colon, thymus, spleen, small intestine, bladder and bone marrow (PubMed:16269462). Strong expression in differentiated adipocytes compared to preadipocytes (PubMed:16269462). Detected in omental fat and subcutaneous fat tissue (PubMed:21982743). By troglitazone and pioglitazone (selective PPARG agonists), by prostaglandin J2 (PGJ2) and by L165,041 (a PPARD ligand), by vitamin D3 and, to a lesser extent, by phorbol myristate acetate (PMA) in the promyelocytic leukemia HL-60 cells. No induction by retinoic acid, nor by clofibrate (a specific PPARA agonist) (PubMed:16269462). Up-regulated by fasting (PubMed:21982743). Belongs to the arrestin family. Extended N-terminus.