This domain lies at the C-terminus of the clathrin-adaptor protein complex-3 beta-1 subunit. The AP-3 complex is associated with the Golgi region of the cell as well as with more peripheral structures. The AP-3 complex may be directly involved in trafficking to lysosomes or alternatively it may be involved in another pathway, but that mis-sorting in that pathway may indirectly lead to defects in pigment granules [2].

1: Characterization of the adaptor-related protein complex, AP-3. Simpson F, Peden AA, Christopoulou L, Robinson MS; J Cell Biol. 1997;137:835-845. PMID:9151686

2: Altered trafficking of lysosomal proteins in Hermansky-Pudlak syndrome due to mutations in the beta 3A subunit of the AP-3 adaptor. Dell'Angelica EC, Shotelersuk V, Aguilar RC, Gahl WA, Bonifacino JS; Mol Cell. 1999;3:11-21. PMID:10024875