2010 Volume 45 Issue 4 Pages 264-267
Gastric proton pump, H+,K+-ATPase fulfills the remarkable task to generate very acidic environment (～pH 1) in the stomach lumen, which is indispensable for digestion and also act as first barrier against bacterial and viral infection. On the other hand, too much acid secretion induces acid-related diseases such as peptic ulcer. Therefore, the mechanism by which this massive H+ gradient generated is considerable biochemical interest. In order to address this mechanism, we have shown the three-dimensional structure of H+,K+-ATPase as determined by electron crystallography of two-dimensional crystals, using liquid-helium cooled cryo-electron microscopy. Here we introduce a molecular model for this remarkable biological phenomenon based on the EM structure of H+,K+-ATPase.