 |  | | | | CFTR regulates the function of other ion channels located within the cell membrane. |
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The CFTR protein also works with other ion channels, including the Outwardly Rectifying Chloride Channel (ORCC), the Epithelial Sodium Channel (ENaC), a potassium channel known as ROMK1 and a chloride/bicarbonate exchanger. These might sound like huge, scientific words, but they really are just other channels that help chloride and sodium to move in and out of cells. When the CFTR does not work, these other channels will not work properly either. The ORCC is a chloride channel that is found on the surface of many cells. Normal CFTR activates ORCC by transporting another chemical called ATP to the outside of the cell. ATP then directly activates ORCC. In CF patients, though, the mutated CFTR cannot transport ATP so the ORCC will not work normally. ENaC is a sodium channel located on the surface of certain cells. Again, when the CFTR is mutated, the way sodium travels throughout your cells is affected. Patients with CF absorb extra sodium. As suggested by its name, the chloride/bicarbonate exchanger transports one bicarbonate molecule out the cell for every chloride that it transports into the cell. The chloride is derived from the efflux of chloride through CFTR. Therefore, if CFTR is not functional the activity of this channel will be greatly reduced. Several other chloride channels are present on the cell surface. The one that may be most influenced by CFTR is the CaCC or Calcium Activated Chloride Channel. The exact protein that creates this channel has yet to be defined. However, it is known that the channel is modulated by the P2Y2 receptor, which is activated by ATP. Therefore, the activity of this channel could be influenced by decreased ATP associated with mutant CFTR.
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