Morphology of clathrin-coated structures at the cell surface.

<p>(A) Confocal optical section of a HeLa cell immunolabeled with antibodies to AP-2 to reveal clathrin-coated structures on the adherent plasma membrane. Selected examples of diffraction-limited spots (arrowheads) and large clathrin assemblies (arrows) are shown. (B) Freeze-etch EM image of the adherent surface of a cultured cell, showing both flat and rounded, budding polygonal clathrin structures (pseudocolored in red) on the plasma membrane and the proximity of budding vesicles to the planar sheets.