Adaptor Related Protein Complex 4 Epsilon 1 (AP4e1)

The heterotetrameric adaptor protein (AP) complexes sort integral membrane proteins at various stages of the endocytic and secretory pathways.

AP4E1 shows an apparent molecular mass of about 140 kD and is part of a 280-kD complex containing AP4B1, AP4S1, and AP4M1. By immunoprecipitation and reprecipitation of HeLa cell lysates, they confirmed interaction between AP4B1 and AP4E1. Immunolocalization of the AP4B1 subunit in HeLa cells revealed that the AP4 complex associates with the trans-Golgi network or an adjacent structure. The association was sensitive to brefeldin-A treatment, indicating that the membrane localization of AP4 is dependent upon the small GTP-binding protein ARF1.