Abstract
The clathrin adaptor protein complex-1 (AP-1) is a central player in cell physiology and human health. It is best known for its role in linking clathrin to its cargo at the trans-Golgi network and endosomes. It participates in traffic important for the correct function of a large number of organelles, including the trans-Golgi network, endosomes, lysosomes, lysosome-related organelles, and plasma membrane. Although it was one of the first clathrin adaptors identified, new discoveries about cargo and pathways that depend on AP-1 continue to emerge. This review summarizes new research into AP-1 that further illuminates its roles in the traffic of plasma membrane proteins, in maintaining TGN content, and in human disease.