Publications

• The Na,K-ATPase.

  Skou J.C., Esmann M.

  The energy dependent exchange of cytoplasmic Na+ for extracellular K+ in mammalian cells is due to a membrane bound enzyme system, the Na,K-ATPase. The exchange sustains a gradient for Na+ into and for K+ out of the cell, and this is used as an energy source for creation of the membrane potential, ... >> More

  The energy dependent exchange of cytoplasmic Na+ for extracellular K+ in mammalian cells is due to a membrane bound enzyme system, the Na,K-ATPase. The exchange sustains a gradient for Na+ into and for K+ out of the cell, and this is used as an energy source for creation of the membrane potential, for its de- and repolarisation, for regulation of cytoplasmic ionic composition and for transepithelial transport. The Na,K-ATPase consists of two membrane spanning polypeptides, an alpha-subunit of 112-kD and a beta-subunit, which is a glycoprotein of 35-kD. The catalytic properties are associated with the alpha-subunit, which has the binding domain for ATP and the cations. In the review, attention will be given to the biochemical characterization of the reaction mechanism underlying the coupling between hydrolysis of the substate ATP and transport of Na+ and K+. << Less

  J Bioenerg Biomembr 24:249-261(1992) [PubMed] [EuropePMC]

• Structure-function relationships of Na(+), K(+), ATP, or Mg(2+) binding and energy transduction in Na,K-ATPase.

  Jorgensen P.L., Pedersen P.A.

  The focus of this article is on progress in establishing structure-function relationships through site-directed mutagenesis and direct binding assay of Tl(+), Rb(+), K(+), Na(+), Mg(2+) or free ATP at equilibrium in Na,K-ATPase. Direct binding may identify residues coordinating cations in the E(2) ... >> More

  The focus of this article is on progress in establishing structure-function relationships through site-directed mutagenesis and direct binding assay of Tl(+), Rb(+), K(+), Na(+), Mg(2+) or free ATP at equilibrium in Na,K-ATPase. Direct binding may identify residues coordinating cations in the E(2)[2K] or E(1)P[3Na] forms of the ping-pong reaction sequence and allow estimates of their contributions to the change of Gibbs free energy of binding. This is required to understand the molecular basis for the pronounced Na/K selectivity at the cytoplasmic and extracellular surfaces. Intramembrane Glu(327) in transmembrane segment M4, Glu(779) in M5, Asp(804) and Asp(808) in M6 are essential for tight binding of K(+) and Na(+). Asn(324) and Glu(327) in M4, Thr(774), Asn(776), and Glu(779) in 771-YTLTSNIPEITP of M5 contribute to Na(+)/K(+) selectivity. Free ATP binding identifies Arg(544) as essential for high affinity binding of ATP or ADP. In the 708-TGDGVND segment, mutations of Asp(710) or Asn(713) do not interfere with free ATP binding. Asp(710) is essential and Asn(713) is important for coordination of Mg(2+) in the E(1)P[3Na] complex, but they do not contribute to Mg(2+) binding in the E(2)P-ouabain complex. Transition to the E(2)P form involves a shift of Mg(2+) coordination away from Asp(710) and Asn(713) and the two residues become more important for hydrolysis of the acyl phosphate bond at Asp(369). << Less

  Biochim Biophys Acta 1505:57-74(2001) [PubMed] [EuropePMC]