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Three distinct and sequential steps in the release of sodium ions by the Na+/K+-ATPase

Nature volume 403, pages 898–901 (2000)Cite this article

Abstract

The Na+/K+ pump, a P-type ion-motive ATPase, exports three sodium ions and then imports two potassium ions in each transport cycle. Ions on one side of the membrane bind to sites within the protein and become temporarily occluded (trapped within the protein) before being released to the other side1,2, but details of these occlusion and de-occlusion transitions remain obscure for all P-type ATPases. If it is deprived of potassium ions, the Na+/K+ pump is restricted to sodium translocation steps3, at least one involving charge movement through the membrane's electric field4,5. Changes in membrane potential alter the rate of such electrogenic reactions and so shift the distribution of enzyme conformations. Here we use high-speed voltage jumps to initiate this redistribution and show that the resulting pre-steady-state charge movements relax in three identifiable phases, apparently reflecting de-occlusion and release of the three sodium ions. Reciprocal relationships among the sizes of these three charge components show that the three sodium ions are de-occluded and released to the extracellular solution one at a time, in a strict order.

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Figure 1: Simplified Post–Albers transport cycle emphasizing two principal Na+/K+ pump conformations: E1 with ion-binding sites facing the cytoplasm, and E2 with ion-binding sites open to the extracellular solution.
Figure 2
Figure 3: Non-conservation of fast charge between on and off voltage steps.
Figure 4: Faster sampling reveals medium-speed component.
Figure 5: Sequential reactions underlie the three charge components.

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References

  1. Post, R. L., Hegyvary, C. & Kume, S. Activation by adenosine triphosphate in the phosphorylation kinetics of sodium and potassium ion transport adenosine triphosphatase. J. Biol. Chem. 247, 6350–6540 (1972).

    Google Scholar 

  2. Beaugé, L. A. & Glynn, I. M. Occlusion of K ions in the unphosphorylated sodium pump. Nature 280 , 510–512 (1979).

    Article  ADS  Google Scholar 

  3. Garraham, P. J. & Glynn, I. M. The behaviour of the sodium pump in red cells in the absence of external potassium J. Physiol. 192, 161–174 (1967).

    Google Scholar 

  4. Fendler, K., Grell, E., Haubs, M. & Bamberg, E. Pump currents generated by the purified Na+K+-ATPase from kidney on black lipid membranes. EMBO J. 4, 3079– 3085 (1985).

    Article  CAS  Google Scholar 

  5. Nakao, M. & Gadsby, D. C. Voltage dependence of Na translocation by the Na/K pump. Nature 323, 628– 630 (1986).

    Article  ADS  CAS  Google Scholar 

  6. Läiger., P. Electrogenic Ion Pumps (Sinauer, Sunderland, MA, 1991 ).

    Google Scholar 

  7. Gadsby, D. C., Rakowski, R. F. & De Weer, P. Extracellular access to the Na,K pump: pathway similar to ion channel. Science 260, 100– 103 (1993).

    Article  ADS  CAS  Google Scholar 

  8. Hilgemann, D. W. Channel-like function of the Na,K pump probed at microsecond resolution in giant membrane patches. Science 263, 1429 –1432 (1994).

    Article  ADS  CAS  Google Scholar 

  9. Heyse, S., Wuddel, I., Apell, H. J. & Sturmer, W. Partial reactions of the Na,K-ATPase: determination of rate constants. J. Gen. Physiol. 104, 197–240 ( 1994).

    Article  CAS  Google Scholar 

  10. Rakowski, R. F., Gadsby, D. C. & De Weer, P. Stoichiometry and voltage-dependence of the sodium pump in voltage-clamped, internally-dialyzed squid giant axon. J. Gen. Physiol. 93, 903–941 ( 1989).

    Article  CAS  Google Scholar 

  11. Läuger, P. & Apell, H. J. Transient behaviour of the Na+/K+-pump: microscopic analysis of nonstationary ion-translocation. Biochim. Biophys. Acta 944, 451–464 (1988).

    Article  Google Scholar 

  12. Wuddel, I. & Apell, H. J. Electrogenicity of the sodium transport pathway in the Na,K-ATPase probed by charge-pulse experiments. Biophys. J. 69, 909–921 (1995).

    Article  ADS  CAS  Google Scholar 

  13. Friedrich, T. & Nagel, G. Comparison of Na+/K+-ATPase pump currents activated by ATP concentration or voltage jumps. Biophys. J. 73, 186–194 (1997).

    Article  CAS  Google Scholar 

  14. Forbush, B. Rapid release of 42K or 86Rb from two distinct transport sites on the Na,K-pump in the presence of Pi or vanadate. J. Biol. Chem. 262 , 11116–11127 (1987).

    CAS  PubMed  Google Scholar 

  15. Inesi, G. Characterization of partial reactions in the catalytic and transport cycle of sarcoplasmic reticulum ATPase. J. Biol. Chem. 262 , 16338–16342 (1987).

    CAS  PubMed  Google Scholar 

  16. Lu, C.-C. et al. Memtrane transport mechanisms probed by capacitance measurements with megahertz voltage clamp. Proc. Natl Acad. Sci. USA 92, 11220–11224 (1995).

    Article  ADS  CAS  Google Scholar 

  17. Bezanilla, F., White, M. M. & Taylor, R. E. Gating currents associated with potassium channel activation. Nature 296, 657– 659 (1982).

    Article  ADS  CAS  Google Scholar 

Download references

Acknowledgements

This work was supported by grants from the NIH. M.H. was supported in part by the Grass Foundation, and J.W. held a HHMI Postdoctoral Research Fellowship for Physicians.

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Author notes

  1. Miguel Holmgren

    Present address: Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, 02115, USA

  2. Jonathan Wagg

    Present address: rSafe Inc, 369 Pine St, San Francisco, California, 94104, USA

  3. Francisco Bezanilla

    Present address: Department of Physiology, UCLA School of Medicine, Los Angeles, California, 90095, USA

  4. Robert F. Rakowski

    Present address: Department of Physiology and Biophysics, FUHS/Chicago Medical School, North Chicago, Illinois, 60064, USA

  5. Paul De Weer

    Present address: Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, 19104, USA

  6. David C. Gadsby

    Present address: Laboratory of Cardiac Membrane Physiology, The Rockefeller University, New York, New York, 10021, USA

Authors and Affiliations

  1. The Marine Biological Laboratory, Woods Hole, 02543, Massachusetts, USA

    Miguel Holmgren, Jonathan Wagg, Francisco Bezanilla, Robert F. Rakowski, Paul De Weer & David C. Gadsby

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Correspondence to David C. Gadsby.

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Holmgren, M., Wagg, J., Bezanilla, F. et al. Three distinct and sequential steps in the release of sodium ions by the Na+/K+-ATPase. Nature 403, 898–901 (2000). https://doi.org/10.1038/35002599

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