Biophysical Journal 90 7

Cover picture: The landscape of membrane domains in RBL-2H3 mast cells as revealed by atomic force microscopy of the cytoplasmic surface. The left image shows raised “islands” within the flat membrane regions that concentrate activated immunoglobin E receptors and associated proteins mediating both signaling and endocytosis. (The scale bar is 1 micron.) The right image is a rotated three-dimensional view of one of the “islands” within the 400 nm square box. In the expanded view, the highest regions (∼70 nm) label with antibodies to clathrin and may represent sites for the internalization of receptors via the budding of clathrin-coated vesicles. See the article by Frankel et al. on page 2404.