Ion pumps

  • Article
    | Open Access

    Cytochrome c oxidase (CytcO) is the last enzyme of the electron transport chain, but how the electrochemical membrane potential affects CytcO is unclear. Here the authors show that proton uptake to the catalytic site of CytcO and presumably proton translocation was impaired by the potential, but electron transfer was not affected.

    • Markus L. Björck
    •  & Peter Brzezinski
  • Article
    | Open Access

    Proton pumps that are driven by light to pump protons out of the cell are involved in the conversion of sunlight into proton motive force; pumps to drive protons in the other direction have been engineered. Here, the authors report the identification and characterisation of a naturally occurring inward-driven protein pump.

    • Keiichi Inoue
    • , Shota Ito
    •  & Hideki Kandori
  • Article
    | Open Access

    Mep2 proteins are tightly regulated fungal ammonium transporters. Here, the authors report the crystal structures of closed states of Mep2 proteins and propose a model for their regulation by comparing them with the open ammonium transporters of bacteria.

    • Bert van den Berg
    • , Anupama Chembath
    •  & Julian C. Rutherford
  • Article
    | Open Access

    The Na+,K+-ATPase moves three Na+ ions out of the cell and transfers two K+ ions in the opposite direction. Here the authors use X-ray crystallography to look at the substitution of two bound K+with those in the medium and show that it occurs sequentially through a narrow gate.

    • Haruo Ogawa
    • , Flemming Cornelius
    •  & Chikashi Toyoshima
  • Article |

    Light-driven proton-pumping rhodopsins are widely distributed in microorganisms and convert sunlight energy into proton gradients. Inoue et al. report the discovery of a light-driven sodium ion pump from marine bacteria.

    • Keiichi Inoue
    • , Hikaru Ono
    •  & Hideki Kandori
  • Article
    | Open Access

    The Na+/K+-ATPase pump exports three Na+ ions for the exchange of two K+ ions, and three transient current components have been associated with Na+ binding and release. Now, these three components are found to be tightly correlated confirming that the binding and release of Na+ions is sequential.

    • David C. Gadsby
    • , Francisco Bezanilla
    •  & Miguel Holmgren
  • Article |

    Proteorhodopsin is used by prokaryotes to generate energy from light. In this study, the authors describe a prokaryote-to-eukaryote horizontal gene transfer of a bacterial proteorhodopsin gene to dinoflagellates, suggesting that these eukaryotes can also use proteorhodopsin to obtain light and produce energy.

    • Claudio H. Slamovits
    • , Noriko Okamoto
    •  & Patrick J. Keeling
  • Article
    | Open Access

    The gastric proton pump, H+,K+-ATPase, contributes to stomach acidification and is a target of acid suppressants. Here, the three-dimensional structure of the pump is determined using electron crystallography, providing the first structural information about the binding of a new class of acid suppressants.

    • Kazuhiro Abe
    • , Kazutoshi Tani
    •  & Yoshinori Fujiyoshi