Abstract
During each complete reaction cycle, the Na/K pump transports three Na ions out across the cell membrane and two K ions in. The resulting net extrusion of positive charge generates outward membrane current1,2 but, until now, it was unclear how that net charge movement occurs2–7. Reasonable possibilities included a single positive charge moving outwards during Na translocation; or a single negative charge moving inwards during K translocation; or either positive or negative charges moving during both translocation steps, but in unequal quantities. Any step that involves net charge movement through the membrane must have voltage-dependent transition rates. Here we report measurements of transient, voltage-dependent, displacement currents generated by the pump when its normal Na/K transport cycle has been interrupted by removal of external K and it is thus constrained to carry out Na/Na exchange8. The quantity and voltage sensitivity of the charge moved during these transient currents suggests that Na translocation includes a voltage-dependent transition involving movement of one positive charge across the membrane. This single step can thus fully account for the electrogenic nature of Na/K exchange. The result provides important new insight into the molecular mechanism of active cation transport.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Thomas, R. C. Physiol. Rev. 52, 563–594 (1972).
Glynn, I. M. in Electrogenic Transport: Fundamental Principles and Physiological Implications (eds Blaustein, M. P. & Lieberman, M.) 33–48 (Raven, New York, 1984).
Hansen, U-P., Gradmann, D., Sanders, D. & Slayman, C. L. J. Membrane Biol. 63, 165–190 (1981).
Chapman, J. B., Johnson, E. A. & Kootsey, J. M. J. Membrane Biol. 74, 139–153 (1983).
De Weer, P. in Electrogenic Transport: Fundamental Principles and Physiological Implications (eds Blaustein, M. P. & Lieberman, M.) 1–15 (Raven, New York, 1984).
Reynolds, J. A., Johnson, E. A. & Tanford, C. Proc. natn. Acad. Sci. U.S.A. 6869–6873 (1985).
Läuger, P. & Apell, H.-J. Eur. Biophys. J. (in the press).
Garrahan, P. J. & Glynn, I. M. J. Physiol., Lond. 192, 159–174 (1967).
Hamill, O. P., Marty, A., Neher, E., Sakmann, B. & Sigworth, F. J. Pflügers Arch. ges. Physiol. 391, 85–100 (1981).
Soejima, M. & Noma, A. Pflügers Arch. ges. Physiol. 400, 424–431 (1984).
Gadsby, D. C., Kimura, J. & Noma, A. Nature 315, 63–65 (1985).
Abercrombie, R. & De Weer, P. Am. J. Physiol. 235(1), C63–C68 (1978).
Garrahan, P. J. & Glynn, I. M. J. Physiol., Lond. 192, 217–235 (1967).
Garrahan, P. J. & Glynn, I. M. J. Physiol., Lond. 192, 189–216 (1967).
Daut, J. & Rudel, R. J. Physiol., Lond. 330, 243–264 (1982).
Karlish, S. J. D., Raphaeli, A. & Stein, W. D. in The Sodium Pump (eds Glynn, I. M. & Ellory, J. C.) 487–499 (Company of Biologists, Cambridge, 1985).
Eyring, H., Lumry, R. & Woodbury, J. M. Rec. Chem. Prog. 10, 100–114 (1949).
Milanick, M. A. & Hoffman, J. F. Biophys. J. 49, 548a (1986).
Glynn, I. M., Hara, Y. & Richards, D. E. J. Physiol., Lond. 351, 531–547 (1984).
Glynn, I. M. & Hoffman, J. F. J. Physiol., Lond. 218, 239–256 (1971).
Shull, G. E., Schwartz, A. & Lingrel, J. B. Nature 316, 691–695 (1985).
Isenberg, G. & Klockner, U. Pflügers Arch. ges. Physiol. 395, 6–18 (1982).
Matsuda, H., Noma, A., Kurachi, Y. & Irisawa, H. Circulation Res. 51, 142–151 (1982).
Garay, R. P. & Garrahan, P. J. J. Physiol., Lond. 231, 297–325 (1973).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Nakao, M., Gadsby, D. Voltage dependence of Na translocation by the Na/K pump. Nature 323, 628–630 (1986). https://doi.org/10.1038/323628a0
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/323628a0
This article is cited by
-
Partial Reactions of the Na,K-ATPase: Determination of Activation Energies and an Approach to Mechanism
The Journal of Membrane Biology (2020)
-
Mechanism of potassium ion uptake by the Na+/K+-ATPase
Nature Communications (2015)
-
Regulation of the cardiac sodium pump
Cellular and Molecular Life Sciences (2013)
-
The dynamic relationships between the three events that release individual Na+ ions from the Na+/K+-ATPase
Nature Communications (2012)
-
Effects of Oligomycin on Transient Currents Carried by Na+ Translocation of Bufo Na+/K+-ATPase Expressed in Xenopus Oocytes
The Journal of Membrane Biology (2011)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.