Once the basic components of the docking complex are assembled with one end of AP-1 bound to cargo molecules, the other end binds to clathrin. Clathrin triskelions polymerize into hexagons and pentagons, forming a cage, which leads to membrane deformation. This polymerization step drives the sculpting of the vesicle. The number of clathrin triskelions required to sculpt a vesicle appears to be variable, but has been estimated to require 36 - 60 triskelions assocaited with 30 - 66 AP-1 complexes. Here a ~380 angstroms vesicle is represented with 48 clathrin triskelions and 52 AP-1 complexes.