A working model for the organization of clathrin and associated proteins at the PPI.

The model shows a cross section through the PPI including a PV organelle and the PM. For endocytic uptake, PM invaginations fuse with PV membranes to create luminal continuity with the extracellular environment. This is the most likely explanation for bulk uptake of fluid phase markers and occasional direct transport to the ER [3, 38]. After uptake, membranes are separated whilst clathrin assemblies remain at the PPI. The distribution of relevant proteins is based on experimental data and functional properties [19]. Dashed lines indicate where membrane remodeling may occur. Circular arrows designate dynamic protein properties.