Ion pumps

Definition

Ion pumps are assemblies of integral membrane proteins, like ion channels, that modulate ion transport into and out of a cell or organelle, leading to generation of electrical signals. Ion pumps, however, work against their concentration gradient, so require energy input, but the energy can also be derived from the concentration gradient of another ion.

Latest Research and Reviews

  • Research | | open

    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
    • , Yoshitaka Kato
    • , Yurika Nomura
    • , Mikihiro Shibata
    • , Takayuki Uchihashi
    • , Satoshi P. Tsunoda
    •  & Hideki Kandori
  • Research | | open

    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
    • , Damien Jefferies
    • , Arnaud Basle
    • , Syma Khalid
    •  & Julian C. Rutherford
  • Research |

    Gram-negative bacteria, such as Escherichia coli, use tripartite efflux complexes in the resistance-nodulation-cell division family to expel toxic compounds from the cell. The CusCBA system is responsible for removing biocidal Cu(I) and Ag(I) ions. Here, the X-ray crystal structure is reported of CusA in the absence and presence of bound Cu(I) or Ag(I). The structures reveal that the metal-binding sites are located within the cleft region of the periplasmic domain. A potential pathway for ion export is proposed.

    • Feng Long
    • , Chih-Chia Su
    • , Michael T. Zimmermann
    • , Scott E. Boyken
    • , Kanagalaghatta R. Rajashankar
    • , Robert L. Jernigan
    •  & Edward W. Yu
    Nature 467, 484–488
  • Research |

    The Na+/K+-ATPase pumps three sodium ions out of and two potassium ions into the cell while splitting a single molecule of ATP. Here it is found that the carboxy terminus of the ATPase's α-subunit is also a key regulator of a previously unrecognized ion pathway. The data indicate that, in the ATPase's potassium-bound state, a cytoplasmic proton can enter and stabilize site III when empty. When potassium is released, the proton returns to the cytoplasm, thus permitting an overall asymmetric stoichiometry of the transported ions.

    • Hanne Poulsen
    • , Himanshu Khandelia
    • , J. Preben Morth
    • , Maike Bublitz
    • , Ole G. Mouritsen
    • , Jan Egebjerg
    •  & Poul Nissen
    Nature 467, 99–102

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