Cells' chemical switchboard isolated.Just as the ear funnels sounds to where nerve endings can sense them, tiny chambers located on cell surfaces gather chemical signals and convey them into the cells. Researchers first observed these structures in cell membranes Cell membrane The membrane that surrounds the cytoplasm of a cell; it is also called the plasma membrane or, in a more general sense, a unit membrane. This is a very thin, semifluid, sheetlike structure made of four continuous monolayers of molecules. in the late 1950s, but only now have scientists isolated them, says Michael P. Lisanti, a cell biologist with the Whitehead Institute Founded in 1982, the Whitehead Institute for Biomedical Research is a non-profit research and teaching institution located in Cambridge, Massachusetts. The Whitehead Institute was founded as a fiscally independent entity from Massachusetts Institute of Technology, and its members for Biomedical Research Biomedical research (or experimental medicine), in general simply known as medical research, is the basic research or applied research conducted to aid the body of knowledge in the field of medicine. in Cambridge, Mass. The chambers, called caveolae, or "tiny caves," keep cells in touch with their neighbors and with their environment, he says. By accident, Lisanti and his colleagues discovered that a particular detergent could dissolve most of a cell, leaving behind caveolae and the cell's internal framework, or cytoskeleton cytoskeleton System of microscopic filaments or fibres, present in the cytoplasm of eukaryotic cells (see eukaryote), that organizes other cell components, maintains cell shape, and is responsible for cell locomotion and for movement of the organelles within it. . Then they found that in a sugar solution, the cytoskeleton sinks while the lipid-laden caveolae float. This makes them easy to isolate and study, Lisanti's group reports in the August Journal of Cell Biology Cell biology The study of the activities, functions, properties, and structures of cells. Cells were discovered in the middle of the seventeenth century after the microscope was invented. (Vol. 122, No. 4). Copies of a protein called caveolin cluster to help form caveolae, he adds. Other researchers had shown that a virus can alter this protein, causing cells to become cancerous. Scientists can now try to determine whether this change affects how cells respond to growth-stimulating substances, says Lisanti. Lisanti's group has found that many other kinds of messenger molecules hang out in caveolae, leading Lisanti to call these cavities signaling organelles. This cellular switchboard may relay many chemical messages to the cell's interior. For example, these messenger molecules suggest that caveolae play a key role in calcium-based signal systems and those involving sugar-containing lipids, called glycolipids. The new findings indicate that some pathogens exploit this access. For instance, bacterial toxins that lead to cholera and whooping cough whooping cough or pertussis, highly communicable infectious disease caused by the bacterium Bordetella pertussis. The early or catarrhal stage of whooping cough is manifested by the usual symptoms of an upper respiratory infection with home in on the glycolipids, then exert toxic effects by modifying signal proteins also in these chambers, Lisanti notes. |
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