Aftiphilin is a component of the clathrin machinery in neurons

Aftiphilin was identified through a database search for proteins containing binding motifs for the gamma-ear domain of clathrin adaptor protein 1 (AP-1). Here, we demonstrate that aftiphilin is expressed predominantly in brain where it is enriched on clathrin-coated vesicles. In addition to eight gamma-ear-binding motifs, aftiphilin contains two WXXF-acidic motifs that mediate binding to the alpha-ear of clathrin adaptor protein 2 (AP-2) and three FXXFXXF/L motifs that mediate binding to the alpha- and beta2-ear. We demonstrate that aftiphilin uses these motifs for interactions with AP-1 and AP-2 and that it immunoprecipitates these APs but not AP-3 or AP-4 from brain extracts. Aftiphilin demonstrates a brefeldin A sensitive localization to the trans-Golgi network in hippocampal neurons where it co-localizes with AP-1. Aftiphilin is also found at synapses where it co-localizes with synaptophysin and AP-2. Our data suggest a role for aftiphilin in clathrin-mediated trafficking in neurons.