The AP2 adaptor complex is a multimeric protein that works on the cell membrane to internalize cargo in clathrin-mediated endocytosis. 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 AP2 adaptor complex exists in two primary conformations: the open conformation (active state) and the closed conformation (inactive state). In its active state, the clathrin binding site found on the β subunit and the cargo binding site found on the μ subunit are exposed to the cytosol, allowing their respective interactions to occur. In its inactive state, the complex experiences a conformational change that causes both sites to be covered, preventing its primary functions. AP2 facilitates the assembly of clathrin lattices when endocytosis needs to occur, by aggregating together with other AP2 complexes, in their active conformation. Here you can see a cryoEM structure showing the AP2 protein bound to the APA domain of SGIP in the presence of heparin (PDB code: 7RWB)
#molecularart ... #immolecular ... #AP2 ... #complex ... #adaptor ... #endocytosis ... #chlatrin ... #vesicle ... #cryo
Protein complex rendered with @proteinimaging and depicted with @corelphotopaint
#molecularart ... #immolecular ... #AP2 ... #complex ... #adaptor ... #endocytosis ... #chlatrin ... #vesicle ... #cryo
Protein complex rendered with @proteinimaging and depicted with @corelphotopaint
