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Voltage-gated proton channels are ion channels that have the unique property of opening with depolarization, but in a strongly pH-sensitive manner1. The result is that these channels open only when the electrochemical gradient is outward, such that their opening will only allow protons to leave cells. Their function thus appears to be acid extrusion from cells2.

Another important function occurs in phagocytes (e.g. eosinophils, neutrophils, and macrophages) during the respiratory burst. When bacteria or other microbes are engulfed by phagocytes, the enzyme NADPH oxidase assembles in the membrane and begins to produce reactive oxygen species (ROS) that help kill bacteria3. NADPH oxidase is electrogenic4, moving electrons across the membrane, and proton channels open to allow proton flux to balance the electron movement electrically5.

References

  1. ^ Cherny, V.V.; Markin, V.S.; DeCoursey, T.E. (1995-06), "The voltage-activated hydrogen ion conductance in rat alveolar epithelial cells is determined by the pH gradient", Journal of General Physiology 105 (6): 861-896, ISSN 0022-1295, http://www.jgp.org/cgi/reprint/105/6/861.pdf, retrieved on 14 July 2008 
  2. ^ DeCoursey, T.E. (2003), "Voltage-gated proton channels and other proton transfer pathways", Physiological Reviews 83 (2): 475-579, doi:10.1152/physrev.00028.2002, ISSN 0031-9333, OCLC 205658168, http://physrev.physiology.org/cgi/content/full/83/2/475, retrieved on 14 July 2008 
  3. ^ Babior, B.M. (1999-03-01), "NADPH Oxidase: An Update.", Blood 93 (5): 1464-1476, ISSN 1528-0020, http://bloodjournal.hematologylibrary.org/cgi/reprint/93/5/1464.pdf, retrieved on 14 July 2008 
  4. ^ Henderson, L.M.; Chappell, J.B.; Jones, O.T.G. (1987-09-01), "The superoxide-generating NADPH oxidase of human neutrophils is electrogenic and associated with an H+ channel", The Biochemical Journal 246 (2): 325-329, ISSN 0264-6021, OCLC 116254550, http://www.biochemj.org/bj/246/0325/2460325.pdf, retrieved on 14 July 2008 
  5. ^ Murphy, R.; DeCoursey, T.E. (2006-08-08), "Charge compensation during the phagocyte respiratory burst", Biochimica et Biophysica Acta, Bioenergetics 1757 (8): 996-1011, doi:10.1016/j.bbabio.2006.01.005, ISSN 0005-2728, http://dx.doi.org/10.1016/j.bbabio.2006.01.005, retrieved on 14 July 2008 
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