Lattices, rafts, and scaffolds: domain regulation of receptor signaling at the plasma membrane

The plasma membrane is organized into various subdomains of clustered macromolecules. Such domains include adhesive structures (cellular synapses, substrate adhesions, and cell-cell junctions) and membrane invaginations (clathrin-coated pits and caveolae), as well as less well-defined domains such as lipid rafts and lectin-glycoprotein lattices. Domains are organized by specialized scaffold proteins including the intramembranous caveolins, which stabilize lipid raft domains, and the galectins, a family of animal lectins that cross-link glycoproteins forming molecular lattices. We review evidence that these heterogeneous microdomains interact to regulate substratum adhesion and cytokine receptor dynamics at the cell surface.