Associates with the adapter-like complex 4 (AP-4) and may therefore play a role in vesicular trafficking of proteins at the trans-Golgi network. Associated component of the adapter-like complex 4 (AP-4). Interacts with active RAB1A and RAB1B, and with GOLGA2. Cytosolic punctate distribution. Also observed in the perinuclear region (By similarity). The RUN domain is required for the interaction with RAB1A and RAB1B.