Functions as an adapter recruiting ubiquitin-protein ligases to their specific substrates. Plays a role in endocytosis of activated G protein-coupled receptors (GPCRs) Through an ubiquitination-dependent mechanism also plays a role in the incorporation of SLC11A2 into extracellular vesicles. May play a role in glucose uptake. Interacts with ADRB2. Interacts (via PPxY motifs) with ITCH, NEDD4L and WWP2. Interacts with AVPR2. Identified in a complex containing at least ARRDC4, AVPR2 and HGS. Interacts with SLC11A2; controls the incorporation of SLC11A2 into extracellular vesicles through an ubiquitination-dependent mechanism. Also found in extracellular vesicles different from exosomes. Belongs to the arrestin family.