A New Way to Cluster
source: http://stke.sciencemag.org/cgi/content/abstract/sigtrans;1/45/ec381
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Science Signaling, AAAS, Washington, DC 20005, USA
The organization of molecules in the plasma membrane plays important roles in mediating signals from the extracellular environment to cytoplasmic compartments. Lipid rafts, which are enriched in cholesterol and sphingolipids, represent one means of grouping signaling molecules at the membrane. Now, Barreiro et al. provide evidence for a functional role for a distinct microdomain called tetraspanin-enriched microdomains (TEMs) in endothelial cell-leukocyte adhesion. Tetraspanins are small transmembrane proteins that associate with various membrane proteins and with cytoplasmic signaling molecules. A TEM on endothelial cells that contained the tetraspanins, vascular cell adhesion molecule-1 (VCAM-1), and intercellular cell adhesion molecule-1 (ICAM-1) was involved in the initial interaction between leukocytes and endothelial cells. In blood vessels, leukocytes adhere to endothelial cells and then can extravasate into the tissues. ICAM-1 and VCAM-1 are adhesion molecules on the endothelial cells that interact with ligands on the leukocytes. Immunocytochemistry experiments indicated that when leukocytes expressing one or the other ligand for these two adhesion receptors were introduced to endothelial cell cultures, both adhesion receptors were recruited to docking structures on endothelial cells
The organization of molecules in the plasma membrane plays important roles in mediating signals from the extracellular environment to cytoplasmic compartments. Lipid rafts, which are enriched in cholesterol and sphingolipids, represent one means of grouping signaling molecules at the membrane. Now, Barreiro et al. provide evidence for a functional role for a distinct microdomain called tetraspanin-enriched microdomains (TEMs) in endothelial cell-leukocyte adhesion. Tetraspanins are small transmembrane proteins that associate with various membrane proteins and with cytoplasmic signaling molecules. A TEM on endothelial cells that contained the tetraspanins, vascular cell adhesion molecule-1 (VCAM-1), and intercellular cell adhesion molecule-1 (ICAM-1) was involved in the initial interaction between leukocytes and endothelial cells. In blood vessels, leukocytes adhere to endothelial cells and then can extravasate into the tissues. ICAM-1 and VCAM-1 are adhesion molecules on the endothelial cells that interact with ligands on the leukocytes. Immunocytochemistry experiments indicated that when leukocytes expressing one or the other ligand for these two adhesion receptors were introduced to endothelial cell cultures, both adhesion receptors were recruited to docking structures on endothelial cells
