Functions as an adapter recruiting ubiquitin-protein ligases to their specific substrates (PubMed:23886940, PubMed:27462458). Through an ubiquitination-dependent mechanism plays for instance a role in the incorporation of SLC11A2 into extracellular vesicles (PubMed:27462458). More generally, plays a role in the extracellular transport of proteins between cells through the release in the extracellular space of microvesicles (PubMed:22315426). By participating in the ITCH-mediated ubiquitination and subsequent degradation of NOTCH1, negatively regulates the NOTCH signaling pathway (PubMed:23886940). Interacts (via PPxY motifs) with ITCH (via WW domains); the interaction is direct and participates in the recruitment of the ubiquitin-protein ligase ITCH to the NOTCH1 receptor (PubMed:21191027, PubMed:23886940). Interacts with ARRB1 and ARRB2; the interaction is direct (PubMed:23886940). Interacts with TSG101; may recruit TSG101 to the plasma membrane (PubMed:21191027, PubMed:22315426). Interacts (via PPxY motifs) with WWP2 (via WW domains); ubiquitinates ARRDC1 (PubMed:21191027, PubMed:22315426). Interacts with SLC11A2; controls the incorporation of SLC11A2 into extracellular vesicles through an ubiquitination-dependent mechanism (PubMed:27462458). Interacts with WWP1 (via WW domains) (PubMed:21191027). Interacts with NEDD4 (via WW domains) (PubMed:21191027). Interacts with PDCD6IP (PubMed:21191027). Also found in extracellular vesicles different from exosomes. The PPxY motifs mediate interaction with WW domain-containing ubiquitin-protein ligases. Ubiquitinated (PubMed:21191027, PubMed:22315426). Ubiquitination by WWP2; promotes localization to extracellular microvesicles (PubMed:22315426). Ubiquitinated by WWP1 (PubMed:21191027). Belongs to the arrestin family.