The α-arrestin family that comprises Arrdc1-5 and TXNIP of proteins are adaptors that function in the regulation of G-protein coupled receptors. Through their PY motifs, Arrdcs interact with the WW domains of Nedd4 ubiquitin ligases and are predicted to act as a bridge between the ligase and their substrates. We have recently reported that Arrdc4 and the ubiquitin ligase Nedd4-2 regulate the iron transporter DMT1 by targeting it into extracellular vesicles (EVs). Arrdc4 colocalises with DMT1 at the plasma membrane, and mediates its ubiquitination by Nedd4-2. However, instead of resulting in the internal degradation of DMT1 as expected, this lead to its release in EVs. These EVs are thought to be plasma membrane derived rather than exosomes, due to the subcellular localisation of Arrdc4 as well as the absence of known exosomal markers Lamp1 and CD63. We have also found that Arrdc4 mediates the biogenesis of EVs, with the number of EVs produced per cell increasing following Arrdc4 overexpression, and decreasing with Arrdc4 knockdown. As Arrdc1-mediated EVs require VPS4a to facilitate their formation, we tested whether this was true for Arrdc4 and found that Arrdc4-mediated EVs instead require Rab11a for their formation. We also generated an Arrdc4-/- mouse to identify the physiological role of EVs and have discovered some novel phenotypes that will be discussed. Since ubiquitination was identified as an important signalling event required to traffic Arrdc4 and its substrates into EVs, we used proteomic approaches to identify proteins differentially trafficked into EVs by Arrdc4, as well as Arrdc4 post-translational modifications and novel binding partners that may be important for EV biogenesis and trafficking. We found a number of phosphorylation and ubiquitination sites on Arrdc4 that we are now testing for their importance in EV trafficking, and several interacting proteins have been identified that are now being further validated.