Neurological disease mutations compromise a C-terminal ion pathway in the Na+/K+-ATPase

Ion-pump structure linked to neurological disease The Na+/K+-ATPase enzyme pumps three sodium ions out of the cell and two potassium ions into the cell while splitting a single molecule of ATP. This process generates the chemical gradients across the plasma membrane that are essential to electrical excitation and ion balance in animal cells. Here the authors determine that the C-terminus of the ATPase is a key regulator of a previously unrecognized ion pathway. Their data suggest that a cytoplasmic proton can enter and stabilize site III when empty (in the potassium-bound state); when the potassium ion is released, the proton returns to the cytoplasm, thus permitting an overall asymmetric stoichiometry of the transported ions. The C-terminus is crucial for pump function as demonstrated by reports that at least eight mutations in the region cause severe neurological diseases.