Component of the Golgi/endosome-localized DSC E3 ubiquitin ligase complex involved in the targeting of the DSC complex to the Golgi apparatus and endosome membranes via the AP3 pathway to ubiquinate Golgi/endosome membrane proteins (PubMed:29355480). Competes with VLD1 to determine the subcellular localizations of the DSC complex (PubMed:29355480). May be required for cell cycle progression (PubMed:12829295). Component of the Golgi/endosome-localized DSC E3 ligase complex composed of at least TUL1, DSC2, DSC3, UBX3, CDC48 and GLD1. Expression is regulated by the metabolic and meiotic transcriptional regulator UME6.