The AP2 adaptor complex is a multimeric protein that works on the cell membrane to internalize cargo in clathrin-mediated endocytosis.[1] It is a stable complex of four adaptins which give rise to a structure that has a core domain and two appendage domains attached to the core domain by polypeptide linkers. These appendage domains are sometimes called 'ears'. The core domain binds to the membrane and to cargo destined for internalisation. The alpha and beta appendage domains bind to accessory proteins and to clathrin. Their interactions allow the temporal and spatial regulation of the assembly of clathrin-coated vesicles and their endocytosis.
The AP-2 complex is a heterotetramer consisting of two large adaptins (α and β), a medium adaptin (μ), and a small adaptin (σ):
- ^ Pearse BM, Smith CJ, Owen DJ (April 2000). "Clathrin coat construction in endocytosis". Current Opinion in Structural Biology. 10 (2): 220–228. doi:10.1016/S0959-440X(00)00071-3. PMID 10753805. (subscription required)