The heterotetramericadaptor protein (AP) complexes sort integral membrane proteins at various stages of the endocytic and secretory pathways. AP4 is composed of 2 large chains, beta-4 (AP4B1) and epsilon-4 (AP4E1), a medium chain, mu-4 (AP4M1), and a small chain, sigma-4 (AP4S1, this gene).[1]
Clinical relevance
It is currently hypothesized that AP4-complex-mediated trafficking plays a crucial role in brain development and functioning.[2]
Dell'Angelica EC, Mullins C, Bonifacino JS (1999). "AP-4, a novel protein complex related to clathrin adaptors". J. Biol. Chem. 274 (11): 7278–85. doi:10.1074/jbc.274.11.7278. PMID10066790.