Functions as an adapter recruiting ubiquitin-protein ligases to their specific substrates (By similarity). Plays a role in endocytosis of activated G protein-coupled receptors (GPCRs) (Probable). Through an ubiquitination-dependent mechanism also plays a role in the incorporation of SLC11A2 into extracellular vesicles (By similarity). May play a role in glucose uptake (PubMed:19605364). Interacts with ADRB2 (PubMed:21982743, PubMed:23208550). Interacts (via PPxY motifs) with ITCH, NEDD4L and WWP2 (PubMed:23236378). Interacts with AVPR2. Identified in a complex containing at least ARRDC4, AVPR2 and HGS (PubMed:23236378). Interacts with SLC11A2; controls the incorporation of SLC11A2 into extracellular vesicles through an ubiquitination-dependent mechanism (By similarity). Also found in extracellular vesicles different from exosomes. Belongs to the arrestin family.