An AP-type membrane coat adaptor complex that consists of beta4, epsilon, mu4 and sigma4 subunits and is found associated with membranes in the trans-Golgi network; it is not clear whether AP-4 forms clathrin coats in vivo. [ http://www.ncbi.nlm.nih.gov/pubmed/10611976 GOC:mah ]
This is just here as a test because I lose it