Fig. 4. Clathrin has a dual role in the maturation of WPBs. (A,B) Clathrin in a supportive role. This is shown by its presence at the tip (A) and in a region where the tubules seem to be organising themselves relative to one another (B) (arrowheads). Bars, 200 nm. (C) Clathrin has a potential retrieval role shown by the classical clathrin-coated vesicle budding from the WPB (arrow). Bar, 500 nm.