InterPro domain: IPR044733

The heterotetrameric adaptor protein (AP)-1 complex consists of one large gamma-, one beta-, one mu-, and one sigma-subunit. AP complexes link the cytosolic domains of the cargo proteins to the protein coat that induces vesicle budding in the donor compartment during vesicle transport [ 1 , 2 ]. In the case of AP-1 the coat protein is clathrin. AP-1 binds the phospholipid PI(4)P which plays a role in its localisation to the trans-Golgi network (TGN)/endosome [ 3 ]. This entry represents the sigma subunit, which comprises a single longin domain and plays a role in binding dileucine-based sorting signals.

1. The clathrin adaptor complexes as a paradigm for membrane-associated allostery. Protein Sci 22, 517-29
2. Deletion mutants of AP-1 adaptin subunits display distinct phenotypes in fission yeast. Genes Cells 14, 1015-28
3. Physiological roles of clathrin adaptor AP complexes: lessons from mutant animals. J Biochem 139, 943-8