Left out: Aquaporin water channels and the exclusion of protons

Abstract

In 2003, aquaporins burst onto the public scene with the Nobel Prize recognition given to Robert MacKinnon and Peter Agre. MacKinnon was awarded the honor for finding the atomic structure of an ion channel, while Agre's role was the discovery of the aquaporins-the major protein that functions as a water channel. In fact, it was Agre that named these proteins "aquaporins." [I]... Elegant mechanisms have been devised to explain these unique properties of aquaporins [2]. An understanding of the role of water and its hydrogen bonds is needed and the maintenance of cell's osmotic and electrochemical potentials is important as well. Earlier studies suggest that a major component of proton exclusion during aquaporin water transport includes a reorientation of the water molecules within the aquaporin channel, breaking their hydrogen bonds [ 1]. Recent studies have questioned the validity of this theory and other mechanisms have been presented [2]. Though the earlier theory suggests an interruption of the hydrogen bond, it is evident that can not be the case, because of the inherent properties of water that rely so heavily on its hydrogen bonds. (from Introduction)